As a moderately skilled human player myself, I developed a foolproof cheese strategy for defeating insane AI. They go crazy if you attack their worker line and recall every attacking unit that's not currently engaged. I played terran and built a single supply depot in the middle of the map to give me enough advance warning when they were coming to attack me, and then dropped 2-3 marines behind their minerals to stall them.
If you do this long enough you can build a virtually undefeatable siege tank army that the AI would simply smash its face into, and then corral them to 2 or 3 bases. They would always run out of minerals while I expanded everywhere and slowly inched tanks forward. Doing this same strategy against humans got me to about gold tier in the early days of sc2.
