One thing I really like about mustashianism is that people are on a reasonably level playing field.
People with low incomes who still save, are just as well off as the people with high incomes who save the same percentage of their income. It's the percentage you save that's important, not how much.
People who have high incomes seem to have a more difficult time being frugal - I have to send my kids to private school, be a member of the country club, have cleaning/housekeeping/maid, my house costs a lot of money in upkeep, I need a gardener... EVERY time we get someone with a really high income, they come out with a similar set of ridiculous excuses.
People with high incomes often also have an investment problem - they may have a lot of investment properties, with huge mortgages, and so have almost no equity in any of them, or be highly leveraged in shares.
My nieces love going to the beaches near where they live. I love going to all the forests that surround where I live. Many, if not most, of the enjoyable thing in life are free, and mustashians love doing these things, rather than wasting money on more expensive (and maybe just as good) things.
It is easy to be envious of others. I could be envious that other people understood FI and ER much earlier than me. I was FI for many years before I realised what that could mean. Consequently, I worked for longer, in some situations that were pretty grim. However, I have done a lot of things in my life (even when it was at its grimmest) that I look back on and am happy that I did. I may not have done those thing if I was retired. I would be a different person. I think I am happiest as I am.