He's obviously miffed at having paid £30 for the ticket at some point, and has seen others buying last minute ones for £5.
We all buy tickets at different times under different deals, some you win, some you lose, but what isn't being appreciated, is if you want your own seat or a specific location, you may pay a premium for that privilidge, and if you want a bargain, maybe chance waaiting till the death and being given a ticket in a crap spot, bit like last minute holiday deals, it's a chance you take.
But don't choose to buy early and then woman if someone else gets a better deal, that's just their good fortune.