Are net gains for a year the only taxable income? Or is every realized gain taxes with only $3k allowed to be offset in the same year?

As many of you know, the cryptocurrency market is VERY volatile and VERY boom or bust. One can make loads of money quickly, and lose it just the same. Each trade from crypto to crypto has been defined as a taxable event.

Example just for simplicity's sake: I put $1000USD into Bitcoin, and then buy some other crypto coin with that Bitcoin I just bought today, and by, say, July 9th, my $1000 is worth $150,000. I then sell that coin back into Bitcoin, thus making a taxable event (I would have a tax liability of $149k here, as I understand it.), and then using that $150k worth of Bitcoin, I buy into another, different coin. By November 18th, my original $150k investment in this other coin has plummeted down to $5k. I sell back into Bitcoin and then back into US dollars.

I started with $1000, ended with $5000, but in between, I transacted a taxable event that incurred a $149k short term capital gain, as well as a taxable event that incurred a $145k short term capital loss.

Does this mean I am liable for the taxes on a $149k net gain? and I would just spread the $145k loss into a $3k claim for the next 48 years? -- or would that only be true if the GAIN was transacted this year, but the LOSS was transacted in 2020? Say you switch out the date "November 18th" for "February 4th, 2020", then you would be fucked. Or are you fucked in both scenarios?

I am in the USA

Thanks in advance.