Only to the point that you get bored and do something useful with your new knowledge.
People enter tournaments for all kinds of games and those tournaments have money prizes and entry fees. I think it's unfair to single out poker since it's a game of skill.
It just so happens it doesn't make sense to play without even the smallest stakes. Otherwise the best strategy is to go all in with any hand and try to double up quickly (if the chips are free, there's no downside to doing this)
Even like $2 buy in games are much tighter than play money games