They are different taxes though. You never pay tax twice.
When you receive money from work, you pay income taxes.
Money just changes hands from one person to another. Everytime that happens, it gets reduced by the amount of taxes that has to be paid which means the government is reposessing that money over time. If you take $1000 and follow its path from person to person, you'll see that over time, it goes to 0 because of taxes being taken out of it every time it changes ownership. And eventually that $1000 is all gone.
some people may say that is fine. but i kind of think like once taxes are paid on that $1000 then taxes should never need to be paid on that particular $1000 ever again. just my opinion.
If you buy Bitcoin with that money and then immediately sell at the same price (let's ignore exchange fees for now) you don't have to pay any more taxes.
You only pay taxes when you sell Bitcoin (or any other asset) at a higher value than what you paid for it. That's capital gains tax. You're paying on the extra money that you have.
You only pay on the extra money, not the initial one that's already taxed.
You can have unlimited capitals gains and taxes on them but you can't deduct unlimited capital losses you can only deduct $3000 per year no matter how much you lost. so its not a fair thing. even with carryover rules, etc. still not fair.