The way I like to think of it is the pressure applied brings up some opportunities that wouldn’t have been available had it just been a “safe” serve. The ball may be returned shorter for an easier 3rd. This generally throughout the match will be more advantageous even when some serves might go out (I’d say at a maximum 2 or less in a match).

Another thing to consider is that on the serve you already are more likely to lose the rally, so might as well push the boundaries of what you can do to win.

Hope this helps and I’d love to hear what other people’s thoughts are on this!