Not sure how their valuation has anything to do with anything.
What are you going on about? Nobody claimed otherwise. Although Fujitsu and Apple would disagree but they're custom ARM designs so not relevant to Nvidia's acquisition.
This again comes from the assumption that the gap is so huge that it takes a decade to catch up, but the catching up has happened in the last decade for the most part. Top x86 IPC has improved about 1.5x over the last 10 years, top ARM IPC has improved over 75x in the last 10 years and continues to have ~20% IPC improvement year-on-year, every single year. At some point these will catch up, and some can argue that they've already caught up (in the case of Apple which is about 3 years ahead of generic ARM).
As you say, x86 has been iterating for top speed logic for 20 years, which is partly true, but they just haven't done much. They had a huge gap (fastest x86 core was more than 150x faster than fastest ARM core just 15 years ago), and it just isn't anywhere near as big as it used to be.
It was always pretty obvious that x86 commitment to compatibility (x86 chips can run 40-year-old binaries) will cost them in efficiency and will slow down progress, as it has happened in the last decade. People unconstrained by this (like ARM) will have a much easier time improving their designs and moving ahead, as we've seen recently.
Yeah? Nvidia won't buy ARM to "keep the value of ARM soaring", they buy it to integrate it into their systems and to use their tech for their own advantage. Nvidia isn't Softbank, they're not buying ARM for its portfolio value, they're buying it because they want to build products with their IP and talent, products that don't currently exist and won't exist without this acquisition.
Valuation means they can buy at one price and sell at another making billions, or leverage that to buy other companies and things.
There is nothing they can't integrate into their systems by licensing ARM IP. They can license specific cores ARM have made or the IP and design their own custom cores, Nvidia has tried to do both before. They can hire people, license the ARM IP and make their own high speed core already. They do not in any way need to buy ARM to make that happen, again it's always been possible and Nvidia have tried to do it several times, remember Denver, remember their custom ARM based chip and x86 interpretor they tried.
Everything you're saying they want to buy ARM for they can do without spending 55billion on ARM in fact they can do that at a great deal lower cost, to the tune of 10s of billions less and then they'd also be in a situation where their cores are custom and not part of a business that sells it's IP.
As said the main reason is likely to diversify because if Intel decided to pay everyone to bundle an Intel gpu with every Intel sold system and most systems have an intergrated gpu that are good enough for most people dedicated gpu market could tank, hard. IN fact with ever increasing difficulty with shrinks there is a huge potential that the only real market that can support constantly increasing power and price for multie die chips in the future will be professional/server markets and gaming might all but get stuck at a given generation without the financial ability to move forwards.
Talking about the gap in performance between x86 and ARM is again entirely missing the point of what I'm saying. The gap in IPC is irrelevant here, making a 4.5Ghz chip requires a different chip design process than designing a chip for 3Ghz. When you first make a core for 4.5Ghz it will not be as good as your third attempt, that's the simple fact of it. If 90% of the performance was good enough then Intel wouldn't still sell to gamers who insist AMD suck. For ARM chips in desktop to compete they actually need similar performance or even better, if you think they'll hit it out of the park on their first attempt then, well, lol. The last 20 years, the gap between IPC is all entirely irrelevant as is the statement that x86 has done nothing for 20 years because that's clearly bull. There are diminishing returns, AMD and Intel gain little by little, but ARM also while accelerating very fast suddenly aren't tripling performance every generation either, because they've hit the same brick walls. Why did ARM architectures increase so much in speed between say 2010 and 2015, but they didn't increase performance between 2015 and 2020 by anything like the same amount? There wasn't the same markets for ARM devices during AMD/Intel's 1990-2010 period so they were shockingly miles behind, then they had a period of easy gains, learning from each generation, low hanging fruit, significantly increasing transistor counts allowing much bigger transistor count gains.
A lot of earlier ARM chips were way smaller and while AMD/Intel were essentially at the larger dies they wanted to use for desktop ARM was making 30mm^2 chips, then they'd move to a new node but also move up to 60mm^2 and actually quadrouple transistor count rather than double. Not surprisingly as ARM chips being made tended to cap out around the 100mm^2 mark due to power/cost reasons then their gains in transistor counts slower significantly and so did performance. From an architectural side every generation you add a bunch of things leaves you shockingly, less things that can be added the next generation. every addition starts costing more transistors, being harder to implement and bringing less benefit.
So no, I didn't make any assumption anywhere that the gap is so huge, it's you making an assumption that because ARM increased their IPC so quickly from 10 to 5 years ago that they can equally close a small gap extremely quickly despite literal mountains of evidence that this assumption is completely ridiculous.
