Elon Musk is conservative with his wealth because it's mostly on paper - he would need to sell shares to get access to it. Johnny Depp's wealth was mostly in cash.
I wouldn't be surprised if Elon Musk only had about $1 billion liquid (aside from whatever goes towards paying known obligations, like the Twitter deal and tax bills), making him only 2x richer in cash terms than Johnny Depp at his peak.
I don't really know or care about the fine details of Musk (or Depp's) wealth. All I'm pointing out is that Musk seems to have a more moderate lifestyle. He doesn't live like the archetype of a rockstar or billionaire.
Byproduct PMU foals cost less than a purebred kitten or puppy sold by a breeder, sometimes as low as $125. With two acres for grazing, annual cost of feeding can be as low as $100-$300 a year for an adult horse.
But, I believe, you are largely correct. I don't think rich people rescue PMU horses.
I wouldn't be surprised if Elon Musk only had about $1 billion liquid (aside from whatever goes towards paying known obligations, like the Twitter deal and tax bills), making him only 2x richer in cash terms than Johnny Depp at his peak.