So Income Tax became somewhat of a thing with the 16th amendment around early 1900’s. (There’s some more history but that’s not important to discuss Capital Gains Tax).
Then the Supreme Court ruled that Dividends and other forms of gains from not income (in plain English), didn’t count as ‘income’. So the Government Couldn’t Tax such as Income Tax.
Eisner v. Macomber (1920)

That Court ruling above, lead into The Revenue Act of 1921, one year later. Where the Government wanted that sweet sweet Income not defined as Income per the Supreme Court. Yea, the government made a new Act to capture gains, Capital Gains Tax.
So Capital Gains tax was only made to recoup Dividends and other things that didn’t count as ‘income’ per Supreme Court Rulings over Income Tax.
In Closing,
From my perspective, the Government didn’t need to create this Act, and they weren’t hurting for money. They just wanted more power to take more money.
It’s evident in today’s world that you look at the Federal Deficit and how much the Government owes and mismanages, and you’d think that this is a cluster fuck. Well, yes, it is, but that’s by Design.
It’s not a bug, it’s a feature.
So even if the government actually needed any of that money, it’s clear that they don’t know how to spend it, especially if they’re just gonna run laundering operations and destabilize other countries. Perhaps, maybe, just maybe, the Government has more money than it needs?
So yea, the Kleptocracy is real. -My Opinion.
If you have a hole in a bucket, the solution isn’t putting more water in the bucket, the solution is plugging the holes. So Hopefully the Department of Government Efficiency removes some of these dumb excess government expenditures. We don’t need more taxes, we need less spending, and people should be held accountable for even Treason if they are committing it.
Take everything I say with a grain of salt, I’m just a random asshole on the internet.
*Not Valid Financial, Legal, Life, or Any Advice