True wealth has a lot of non-financial measures.
Non-financial goals are way way harder to achieve than FIRE: the biggest issue is selecting your non-financial goals. Money is a simple goal and it isn't impossible to achieve - then what?
Deciding that money should be your primary focus overoptimises for financial wealth against non-financial wealth.
For example, life satisfaction: do you know people doing jobs they love? People that would continue their calling even if it didn't pay them? Try to understand their wealth even if they don't have the financial freedom a successful business can give you. The main problem is most of those jobs are not in businesses and it is hard to understand things we haven't experienced. Jobs are a very poor example but you get the idea.
I've retired early: for me personally, financial wealth is not enough.
One limited resource that we are approximately all given the same amount of is time - you get fifty years between 20 and 70 to use the best you can. I think most people don't use their limited resource very well (even those that optimise their time well seem to use it poorly on bad meta-goals).