All of those alternative sources of money require an individual to already be quite wealthy: capital income means capital assets; gifts/inheritances means wealthy family. At that point...it honestly doesn't matter how you get your money. Over my career I have provided tax consulting and compliance services to many HNW individuals, and income taxes were never once a disincentive to working. A person rich enough to choose how they earn their income works because they choose to.
(Note: payroll taxes such as FICA, etc., actually phase out pretty quickly after $100k in earnings, so they're regressive in nature. There is the high-wage supplemental tax, but this is offset by the cap on income subject to SSI tax, so workers earnings more than $140k actually pay less in payroll tax.)
That being said, I agree that capital gains should be treated as regular income (as it was historically, pre-Reagan) and that income received via gift/inheritance should not receive a FMV cost basis.
(Note: payroll taxes such as FICA, etc., actually phase out pretty quickly after $100k in earnings, so they're regressive in nature. There is the high-wage supplemental tax, but this is offset by the cap on income subject to SSI tax, so workers earnings more than $140k actually pay less in payroll tax.)
That being said, I agree that capital gains should be treated as regular income (as it was historically, pre-Reagan) and that income received via gift/inheritance should not receive a FMV cost basis.