I was originally planning to end this post with "or just making up some numbers", but since GP was writing of a joke investment, active gambling seems to be a reasonable assumption. And putting in 50£ in a toy account (and never extending it with fresh money), leaving with 18 after years, that also doesn't seem like an unreasonable thing to do. That's lower stakes than meeting for an amicable 2£ per player poker night once a month. If the stated goal of a joke investment is a dividend in entertainment, then passive is a terrible investment strategy.