In short, it's for pvp and I'm a masochist lol. After I finished making the character and got to RL65. I for some reason took the challenge to see how far I can get pve wise. Mostly because I was able to beat the game on RL80 save... and yea... those 15 levels have been very noticeable
Oh I get it. I've got many pvp builds that have undergone the same ordeal. I don't know if you coop or host, but if you are an invader at rl65 you will invade rl90s (rl64+ hits rl90).
Rl90 is kind of a major pvp level for people to park on. (Usually with +17/7 upgrades) so if you are finding yourself getting smacked around invading at rl65 you're probably hitting that rl90 plateau. I had an rl66 build that I finally brought to rl90 for that reason and enjoyed it a great deal more.
But for your enjoyment by all means keep on the challenge! Good luck!