That just isn't true, look at any richest people in the world list right now, look at who the top people are - IT nerds!
Look at where Prince Harry just got a job, a decade or two ago a prestigious job might have been at some big bank or consultancy, these days a C level role in a tech firm is fit for a Prince.
There are plenty of tech-related roles in very high demand right now from security professionals to data science... there is always demand for good developers - a good developer has a heck of a lot of freedom, generally a fat salary or daily rate and can change employers very easily.
Even mediocre devs and BAs in London can opt to go contracting and get the standard-ish £500 a day + or - £100.
Good developers (or BAs) with in-demand skills can get substantially more in the contractor market.
As for start-up employees or indeed salaried professionals at private companies that later go public they can end up with some serious wealth if it goes wrong... I know of someone who spent circa a decade in the same company as it grew (not a high growth start-up or anything, just a regular, profitable, private IT company) - he had stock options and made use of them over that decade... the company then went public, he's a multimillionaire now and never needs to work again. He wasn't a founder, he didn't join some high risk, high growth firm... he was a regular joe starting in some grad role at like 30k a year and then over the years working his way to a middle/junior management position with responsibility for a small team.
I think the problem is people think of "IT" as - people who fix the printer etc.. and there are career paths within the broad umbrella of "IT" that involve working on a help desk or doing mundane jobs + collecting vendor certificates in order to do more mundane jobs... then eventually working your way up to a position where you're an expert in fixing mundane stuff and you're only called to fix the particularly tricky things that the layer or two of minions below you can't fix.