At lvl 50, is it possible to find upgrades?

Pretty much depends on RNG, but I am quite optimistic that base on self gear alone you can get to level 70 without problems. But mostly it is ok to self gear to lvl 75 or 80 through grinding and crafting. After that it is more rational to trade items to get decent gear for mapping.

I think a lot of this is great advice but if you are concerned about RNG you will hit a wall eventually and this is very build dependent. There are builds that crush Merciless and later but suffer through the rest of the game, there are a few that crush early and lose a little steam later if you don't have right buffs/gear. Like in all of these games either you die to often because you can't kill fast enough or you don't have the right resists or you can't take any damage and aren't ranged. I usually look for trades in Cruel, there is a wall there unless you have very safe build. Try an LA build to start, even I managed to pull that off ok and I wasn't really stocked with good stuff.