I used to have a problem with slippery picks, then, 30 odd years ago, the late Pete Sayers convinced me to try dunlop polythene picks, which don’t slip anywhere near as much. (There are also ones with holes which helps to some extent.) more recently, I’ve gone back to the celluloid ones and I don’t have a problem.

I suspect that it depends on the degree to which you grip your pick set against the force you use to pick a string with it. With half decent PA systems and many more people plugging in, there’s no longer much need to hammer the hell out of a guitar in order to be heard.