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).
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!
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.