When I was a kid I used to dream about being involved in space launches and designing jet engines and things like that. They were big but achievable dreams, and in fact I have achieved them. At certain moments I stop being my adult self who carries around a history of gradual effort and advancement, and I go back to being my kid self and I just say, "I can't believe I'm doing this." For example, when I gave a presentation to NASA on how to fix a certain part of the Shuttle after the Columbia accident, for a few seconds I became my 12-year-old self who launched model rockets from the backyard, and I said, "I can't believe I'm doing this." That was also the time I am sure I felt my grandpa standing behind me, in his high boots, all covered in coal dust.
I have several friends who must have had the same beautiful and frightening experience, like my friend from high school the standup comic who did a set on Leno. I bring this up not to brag --- my dreams probably sound boring to some people, and that isn't the point. I bring it up to make the point that there are certain experiences money cannot buy. It's not just greeting-card bullshit. You cannot buy the experience of discovering a law of physics or painting a masterpiece.
You may say, well, Elon Musk spent $1 billion because he wanted to build his own rocket. That's true, but the $1 billion by itself didn't get him all the way there. He didn't just give some people $1 billion to go off and design a rocket he could slap his name on, he actually designed the damned thing. (With help from a lot of other people, of course, but he was the driving force.) When the rocket launches, it is primarily by his own hand.
This is what I try to explain to my kids when they talk about careers. Like most kids, they would prefer to get rich, but what is the point of money if not to enable you to have certain experiences, even if it's just the experience of living in a 5th Avenue penthouse? But there are experiences that money can't buy. Lots of people have donated money to try to cure cancer, but they cannot buy the experience of actually curing it. Would you rather be the billionaire whose money enables cancer to be cured, or would you rather be the person who cures it?
Come to that, you can't buy the experience of living every day of your own life, whether your situation is happy or sad. You are the one who gets to live it --- or choose not to do so, I guess. This is what Steve Jobs meant when he said "Your time is limited, so don't waste it living someone else's life."