How come it takes so long for arteries to block up from plaque even when you hsve all the risk factors?

Luck: good vs bad: There are many factors that go into blocking an artery, including good vs bad luck. Even with many risk factors, you may not suffer from clinically apparent disease while others w/just one risk might suffer a catastrophic event. Slow build up of plaque takes time while abrupt plaque rupture is almost instantaneous. Regardless, it's best to reduce/optimize all risk factors as best as possible.