Lately, wait lists are more often a manipulation by colleges than a realistic chance, especially at more competitive schools, although occasionally people do get in off wait lists. In 2018, Brown actually put more people on the waitlist than it had spots in the freshman class, which is utterly ridiculous.
2020 update to the above: Some schools, including Brown, seem to have reacted to the recent bad publicity about misuse of waitlists by either accepting students off their waitlists (Brown last year) or waitlisting a more reasonable number of students. This link provides information about waitlist statistics at a number of schools from 2019 and information about when waitlist decision are likely this year. It's updated fairly regularly: https://www.collegekickstart.com/blog/item/class-of-2024-waitlist-notification-dates-and-stats?utm_source=newsletter_662&utm_medium=email&utm_campaign=alert-class-of-2024-waitlist-notification-dates-and-stats
Some articles here also deal with being rejected outright, which is in some ways kinder even if it doesn't seem so.
The Lori Gottlieb article below is excellent:
Lori Gottlieb (The Atlantic's Therapy Column Writer) on College Rejection 20
How to react if you're waitlisted 22
A COLLEGE REJECTION MELTDOWN IN 5 EMAILS 17.DOCX
ARE WAITING LISTS OUT OF CONTROL 18.DOCX
GETTING REJECTED FROM ELITE UNIVERSITIES18.DOCX
MAKING SENSE OF ADMISSIONS DECISIONS 17.DOCX