I'm not sure that we were necessarily the richest or at least the richest clubs were not "that" rich. We also had quality throughout our squad a lot of the time, perhaps just not quite the very best quality in the world though.
Once the glazers took over as well we were never close to being the club with the most cash to spend. You also couldn't necessarily just buy any player you wanted as they may have preferred another club.
We should have been buying more top players over the years but we won the PL most years so I don't think there was ever a huge desire to spend big at the club.
Either way, yes I agree that we should have won more outside of england over the years.
You were undoubtedly as rich as anybody in Europe pre Abramovic. As I said, there was no excuse for not having a side capable of winning the CL. I happen to think your sides over the years have been good enough but you underachieved.
Fair point re the Glazers but the money only started to tighten up around the time Ronaldo left. That's still a good 15-20 years where Utd should have been able to challenge year in year out.