You are making an assumption that I machine gun the shutter.
I have never used burst mode, ever, not once. Each shot I take is selective and I may take 2 or 3 shots of the same thing but that is not common and I usually take one and move onto to the next.
I may go through 150 shots when I get home and they are all of different things but 90% haven't turned out as well as I'd hoped (mostly from a composition or interest point of view rather than technical errors)
I delete around 90% as I am a very decisive person (who also hates clutter and disorder - mild autism!) and if I don't really like a shot it gets deleted. I don't hum and har, I make an instant decision and if it is not good enough it is straight in trash.
I don't really look at the shots on the camera and don't delete at source as I find it better to look at the full size shots on a computer when I get home as the whole process is much quicker and easier (tab to next shot, press delete) so all of my shots come home with me.
Interestingly enough I was using film a few months ago and found I typically liked about 4 photos from 36.
One last point, if I went through the 10000s of shots of the people who keep all of their shots I would most probably delete 90% of those too. Not because they are bad photographers (they are very likely to be better than me!) but because the shot does not warrant keeping.
Sorry, went a bit ranty - not intended at you - just wanted to give the background to why I delete so many