How can someone be level 47 in Seasonal? [Discussion]

My buddy got killed by a level 47 player on Saturday The guy had something like 7k hours in the acc.

How is it even theoretically possible for someone to be level 47 now? Wasn't the season on for ~5d days by Saturday?

For the amount of XP it takes to get to lvl 47, I don't think it's actually feasible?