Is this why my PFR keeps going up?

[Shillx]

77 is not a weak hand in a multiway pot. It is a great hand heads up and when people are playing all types of bad multiway hands (like T7o and such). If you hit a set, you are hoping that people will chase gutshots and overcards and backdoor draws by making the pot bigger preflop. You raise here for much the same reason that you would coldcall in a multiway pot.

Brad