Just a sparse list to get this going. Ok, so here we go...
Sagliophobia
The fear of beginning Level 5 with fewer than 140,000 points.
Chienophobia
The fear of a world record attempt disrupted by an obnoxious spectator's constant declaration, "Hey Doc, my elbow hurts when I do this..."
Willmsophobia
The fear that every fireball in existence is a "jerk".
Staalophobia
The fear of falling through an open rivet hole.
Vincophobia
An unnatural fear of the number 2700.
Psarophobia
The fear of being forced, at gunpoint, to play at 1.2m pace for 8 consecutive hours.
Davophobia
The fear of having a masterful 1.14m game rejected by TG, due to a submitted video that consists of 2 hours 41 minutes of a dog relaxing on a sofa.
Vonophobia
The fear of playing DK without the aid of an infectious techno soundtrack.
Stellaphobia
The fear of broadcasting embarrassingly poor gameplay on Twitch TV.
There's no shortage of imagination on this forum. Feel free to be creative, and add a few "phobias" of your own.