I'm not sure exactly the wording that conveyed that to you, but there's generally a lot of leeway in what "the best you" means. Generally, that means the happiest you, and people take different paths to what they think will give them that happiness. For some, that's a very ambitious work schedule, or work related hobbies. For others it may be plenty of time for family or fun. It can be any combination of this, but in the US, "success" is very malleable (or or less so depending on your social circle and geography, but still on the malleable side). When someone drops out of a high stress job to do something like open a small business or change their lifestyle, I don't think the consensus is that people think they failed, but that they are happy that the person found something they presumably enjoy. I know that's how I feel when I hear about it.

But that's the important thing to consider on the other side, some people enjoy their jobs, or the fields they work in even if their job is currently annoying, and they may choose to spend their own time in ways related to their day job. This doesn't have to ambition or someone driving themselves to improve (but it can be). It can just as easily be someone that got a job doing something they love, so they do similar things in their free time.