Firefox has 8-9% desktop market share in Europe, 16-18% in Germany. So in some important markets it’s still pretty relevant.

Wasn't Opera's (the good old Presto one) marketshare also 1% back then? And it was still considered major (even though it had compatibility problems mainly caused by sites ignoring the standard)

It's more than 2% when you condition on things like "lives in US" or "lives in EU" or "is using a desktop." e.g. among German desktop users it's apparently more like 20%. Most people probably aren't targeting global traffic and should never consider it since it can be extremely misleading.

One in every 50 people is a lot of people.

Over 6% on desktop (which is where I do the bulk of my browsing...).

More than Safari.

It's in the top 5.

It isn't more used because one browser is promoted by the biggest search engine and thus has two thirds of the market, and the other two come pre-installed with the OS.