Why don't we use this hack IRL?

Probably the annoying taxman who takes 20% of your $infinity, which just so happens to also be $infinity.

Your infinity is larger though so it's all good.

Not quite, anything subtracted from itself is zero. However, if you send me Infinity bitcoin, I will send you 10 Infinity bitcoin back (I am Expert Hacker).

Relevant reading: https://www.quantamagazine.org/how-can-some-infinities-be-bi...

No, not all infinites are the same. For example uncountable infinites are all larger than countable ones.

Bah, you could never convince me aleph numbers are real!

Reminds me of Hilbert’s paradox of the Grand Hotel

https://en.wikipedia.org/wiki/Hilbert%27s_paradox_of_the_Gra...

I think if someone takes 20% of your infinity you are still left with infinity?

To be accurate, you're left with undefined. But not really, the taxer actually controls infinite, person paying the tax has to figure out how to divide their infinite up.