Depends where you are. If you're in the San Francisco area, you'll see a lot of people display Grateful Dead logos - eg bumper stickers on cars, t-shirts, or even cufflinks (I've met quite a few senior executives who were 'deadheads' at one point, same way you'll run into all sorts of people at a Burning Man event). You can safely assume anyone showing off their Grateful Dead affiliation has tried LSD at least once.
One reason people don't talk about it much is that if someone is arrested and has LSD, the amount in their possession for evidence purposes is based on the weight of the delivery medium, usually blotter paper. So what you might think, that's only a few milligrams per square. Unfortunately the standard dose, which is soaked into the paper, is about 50-100 micrograms. Thanks to the 1986 anti-drug legislation and the 1991 Chapman decision, the weight of the blotter paper was included as part of the 'mixture containing LSD' without regard to the very low dose:carrier weight ratio, so even a modest amount owner for personal use could easily pass the threshold for a presumtive attempt to distribute, attracting a long sentence.
This has been fixed to some extent in the most recent edition of the Federal Sentencing Guidelines, but that was only last year, after 20+ years of really jacked-up sentences. Now the sentencing commission assumes a carrier weight of 0.4 milligrams (vs. a base dose of 0.05ug for the chemical itself: https://books.google.com/books?id=TbJlhRCG4NYC&pg=PA164&lpg=...
Here's the current drug quantity table, which sorts people into different groups depending on the amount they possess: http://www.fd.org/docs/select-topics/sentencing-resources/cl...
This still seems an order of magnitude too low to me; a quantity suitable for personal use could put someone away for a couple of years. So it's not the sort of thing that people flaunt openly the way many marijuana devotees do.