The goal of the FIRE movement is financial freedom, independence, or however you frame your ‘why?’.
Frugality is a mainstay of the FIRE movement because you’re saving money for your future. Essentially a penny saved is a penny earned.
Now being frugal does not mean that you deprive yourself but it means that you determine what adds meaning to your life. If it does not add or improve it… then what is the point.
Frugality is laying down the groundwork for a prosperous future.
Sure, it would be nice to live in luxury now. However, you might be paying for it for the rest of your life in terms of debt. Which just sucks more of your hard-earned money and your time away.
Being a little frugal now prevents that from happening, perhaps you will never live in luxury but you will be comfortable.
In addition, frugality also allows you the skills to weather the bad times. If those skills are never learned from a young age then those bad financial times can be a death sentence.