yes.. i know basic probability theory.. still says that in a large sample, 1 in 5 should pop.

You are falling into the gambler's fallacy. Yes, the average is expected to come out to 1 in 5 as the sample gets very large (as in, the limit approaching infinity), but each individual attempt is always 20%. When looking at probability for independent events, what already happened doesn't matter. There is no corrective force that says that because you failed 20 times, the 21st time has to succeed because you're not getting a 1 in 5 average for your actual attempts. Your next RE is still a 20% chance to succeed.

To put it another way, if you said you should expect around 200 successful REs out of your next 1000 tries, that'd be reasonable. If you've done 999 REs and failed and you expect your next attempt to be anything but a 20% chance at success, you'd be wrong. (And probably cursed.)