I've noticed that a lot of people who are born rich still choose to work.
And in some cases, that might still end up being much more lucrative than a "normal job". But I'm sure that in many cases, it doesn't - we just don't hear about it, because they're still rich, and nobody really knows what they're really doing anyway.
There are plenty of people who were born rich who nonetheless go to work everyday. They are engineers, doctors, lawyers, consultants, bankers, inventors, teachers, professors, and business owners.
Having money doesn't discourage people from working. We won't run into a shortage of astronauts, teachers, or even police officers. But we may find it difficult to find people willing to work as a janitor for $8.00 an hour.
Such an attitude would certainly apply to their reasons for working.
After all, there's a practical limit on the value of a person's labor - let's postulate that it's around $7,000 a day - there's no such limit on what investments can return in a day.
* $7,000 is Elon Musks's $2.2M salary from 2019 divided into 340 working days.
First: musicians and athletes in their prime can make more, and that's definitely labour income. Second: if a bus were to hit Elon Musk or Jeff Bezos or Warren Buffett, their companies would lose lots of value. So even though their day-to-day income looks like it's coming from investments, a big part of it is actually labour income.
(I'm taking 'hit by a bus' here as an exogenous event that would make the CEOs unable to work, but wouldn't touch the companies at all and crucially wouldn't imply to investors any other information about the companies.)
Similar for running a hedge fund: as far as the tax man is concerned, a lot of the income they generate for the people running the fund is some kind of capital returns. But in an economic sense, it's mostly labour income: if you want to estimate the capital side, just see how well the hedge fund's customers are doing out of their investment; any returns insiders make above that are labour income.