Is it even possible to solo the deep dungeon?

[Cherub]

Yes. Some already did. But it grants you nothing in addition, so doing it alone is nothing but a huge waste of time.
Well you can say "I did it alone" - Congrats, in that time I finished my second Weapon xD

Congratulations on your weapon but since I already have 235+ weapons, none of them are of interest to me.
It grants me nothing but a challenge which is why people like us are even doing it.
It's no use telling people it's stupid to do because it isn't for us. We're after a challenge and prestige and the feeling of accomplishment. Not some weapons with the ilvl being the same and lower as the ones I already have.

Also, Floor 50 cleared! on BLM Solo. It's not impossible (as DPS)...well maybe for MCH it is :v