I bet on football fixed odds, since I'd be following the football anyway and can kid myself on that I know enough about it to make "informed" selections. Quite often it's because I'm working at the weekend. I have a telly at my desk and having a couple of lines on makes the Vidiprinter on a Saturday afternoon more interesting.
It's very much just a hobby though, it's never going to be a ticket out of the ghetto. On a good month, typically, it's self-financing for the next month. On a bad month, it isn't and I wait until the start of the next month to top up my stake. On the very rare occasions my winnings stray into three figures it's a Weakest Link-style BANK! from me.
I can see how people would get into trouble with it though, if you were of an addictive bent - having it on an app on a phone, given the astonishing volume and cleverness of ads for online bookies while you're watching sport on TV, for example, seems to "normalise" gambling from what was once considered a vice, that you had to go into a seedy bookies' shop reeking of fag smoke and despair to partake in, into an everyday activity that is as easy as posting on Twitter or sending a text.