I'd say your analysis is flawed solely because we don't play paintball for 7 hours across any format. Lets consider the various formats of paintball you can play.
rental days: a £40 package may get you around 700 paintballs at a site with good deals, less for bigger chains. This would last any normal player between 6 and 8 games I'd say, and if game time averages out at 30 minutes each (which it won't as most normal rental games last 10-15 minutes max) you're going to play an absolute maximum of 4 hours. realistically you'd be lucky if you actually play any more than 1.5 to 2 hours. real cost of 7 hours play: £140
scenario games: much longer game time, main sunday games will probably run for around the 6 hour mark total. Ticket costs for weekend events are in the region of £80 not including any paint, travel, accomodation, food etc. So again, being conservative with paint you might be able to get away with using a case of paint per day, but lets be honest you won't see much action over 6 hours with 1 case. So again, once you include a reasonable amount of paint as well as other miscellaneous costs for the weekend, most players will probably spend on average around £80 per day at a major scenario event. real cost of 7 hours play: £93
Tournaments: Well the cheapest tournament I've ever been able to play is student cup and thats because its pretty much zero profit arranged by students themselves. At the event just the other week my team probably spent around £120 per person for 2 days play including the cheapest accommodation and transport. So £60 per day for around 8 games with regulation time of (i think) 12 minutes each. 90% games finished well within regulation time but thats still an absolute maximum of 1hr 14mins of playing paintball. real cost of 7 hours play: £300. I wont even begin to scare anybody by calculating the cost per hour of play for major leagues like the millennium. I'm sure I calculated for a CPS event i played that it worked out something crazy like £20 every point i played, some of which i might be shot of the break after a few seconds.
So yes its still not the most expensive hobby in the whole wide world but we can't pretend that its cheaper than some of your examples like watching football or going to the cinema. Those calculations I've made are all VERY conservative and are likely to actually be a lot higher in practise for most players. and it also doesn't include any costs at all for equipment which most people will buy.
Is it still worth playing? absolutely in my mind but it is definitely not a small budget hobby.
