I managed to get a combo of 178 with the skill that uncaps the multiplier. Don't ask me how.
Apparently the second equipment slot is broken on all 3 characters too. Depending on what you select first, if you try to equip something to it it will either remove the item from your inventory or crash the game.
You know you can still sacrifice used stat points after learning all of the skills, right? That feature exists for a reason.