I made ~100k investing in Bitcoin learned afterward that I needed to pay capital gains taxes on it in the amount of ~23k (via https://bitcoin.tax/).
What are my options in terms of not paying so much gosh darn money?
You can reduce your capital gains taxes in two ways (USA), off the top of my head:
You need to meet a woman (or man if you are in a state that allows same sex marriage) who has a carried forward loss or other loss that exceeds the $3K/yr they can take against their own income. If they had a loss of $200K some time ago, and are taking $3K/yr, they may still have $100K they can offset with you. Marriages have been based on less than this.
Break the sale up over several tax years so that you don't have a spike in your income pushing you into a higher tax bracket.
Don't sell it until you retire, when you're probably in a lower tax bracket. (If you're 20, this may be impractical.)
Get some other deductions, like medical expenses, charity, etc.
Failing that, maybe a couple of other ideas that neither of us thought of, I think the real answer is: suck it up and pay the taxes. If there was a way to reduce your taxes just by checking the right box on a tax form or some such, everybody would do it and the government wouldn't collect any taxes.
If you only have to pay 23k federal taxes on 100k, that means you are in the long term capital gains tax rate, which is the lower of the tax rates available.
First you get your federal income tax marginal tax rate, and then find the matching long term capital gains tax rate. For example, if your marginal federal income tax rate is 28%, your capital gains tax rate would be 15%. Or rather, if the amount of the gain would put you in the 28% rate, then your long term capital gains tax rate is 15%.
You can reduce that by having more losses. If you have anything else invested anywhere that is taking a loss, then you can sell that this year and it will offset the other gains you have realized. The only note is that your losses have to be long term capital losses too.
Tax loss harvesting takes this to an extreme where you sell something at a loss to lock in the tax loss, but you didn't really want to get rid of that investment, so then you buy a nearly identical investment. ie. if you owned shares of "Direxion Tech Sector ETF" and it was at a loss, you would sell that and then immediately buy "ProShares Tech Sector ETF", the competing product that does the exact same thing.
Then there is charity. This still requires spending money and you not having it any longer. If you feel that a cause can use the money more directly than the US government, you can donate an appreciated asset to the charity - not report a gain and also take a charitable deduction.