Clearly you need to do the maths about how much people attending a football match actually put towards the purse, you'd be surprised at how little it is. Just think of this... a shortfall of about 5k in attendance (which is usually all we're ever off capacity, and that usually when the likes of Fulham are at VP) with an average spend of £40 equates to £200k, now as that happens on average about (without doing the research) say 12 times a season thats a whole £2.4mil (£2mil net) over a season we're falling short through "poor attendance". Who you going to buy and pay wages for because that £2.4 mil is missing? is poor attendance really preventing us moving forward as suggested? I think not, its guff. It may be well intentioned but its not really the truth of the situation. The attendance shortfall is worth about half a Marlon Harewood financially.....(wages not included)
Looking at it in that sort of isolation, then yes. 5,000 extra fans at a few games won't do that much for us. But the importance of matchday revenues can't be overstated.
Arsenal and Manchester United make more than £100 million per year on matchday revenues (tickets and spend within the ground). Liverpool, a club of similar size, make about £40 million. That £60 million is two times Fernando Torres + wages.
Obviously we aren't going to be pulling in all that extra, but we need more fans and (to be honest) we probably need those fans to be spending more money if we want to compete. (Whether we want to compete if it means pricing our fans out like many United, Arsenal etc fans are is another question.)
Even the £2.4 million you mentioned - it might not be enough, but it could be used as £800,000 each per year that might have kept/keep Barry, Milner and, say, Young. Not saying that would be the ideal situation or anything, but you shouldn't dismiss it all as guff or just look at that £2.4m in isolation.