8% of people used it at least one time in an entire year.

In a place where people (who have on average very low incomes) were given $30 worth of bitcoin by their government just for signing up to a wallet app, so a very, very large proportion of the populous (compared to any other country on Earth) already had an app and wallet set up and ready to go. That's not a lot. That's a clear indication that the experiment simply didn't work.

Depends for what. What were Bukele's stated goals? Only with this in mind can we decide whether 8% is high or low.

Doing better than Firefox

This "everything's going great as long as you squint hard enough" stuff is why people don't give cryptocurrency proponents the time of day. At some point admitting you've lost actually better preserves your ability to be heard at the next debate.

When I consider 8% to be high and you don't, that makes me more skeptical of mainstream adoption as a currency than you are.