The thing is, normally most people done have ANY hand sanitizer, let alone two, as you describe.... so when suddenly everyone wants to buy them, there isn't enough for everyone to have even two. That doesn't make the people buying them selfish.
COVID-19 isn't going to be some world ending thing, it's just going to put some supply pressure in the short term until production and distribution can ramp back up, but people are treating it like it will be. It's really frustrating.
If nobody hoards, everyone is fine.
If a small number of people hoard, there are stock-outs, and everyone else has no access to the thing.
Ergo, the strictly dominant individual move is to hoard ASAP. As it provides coverage against all scenarios.
Limiting quantities is the obvious equitable response to this, so it's been good seeing retailers step up and do so.