It's not about competing with Chelsea and Man City though; that is highly unlikely to happen any time soon unless the face of football dramatically changes. We need that money to compete with the likes of Newcastle, Villa and West Ham...the kind of clubs that conceivably we could be perceived of in the same bracket if we produced consistent progress for a number of years.
If West Brom get relegated this year and we don't go up, they are going to be so much better off than us in financial terms that we won't even be on the same page, despite being in the same division. That's why we need to be in receipt of regular PL money under the current setup because if not, we'll fall behind our natural peers let alone those we've been lagging behind for 30+ years. Look what being out of the top flight for a decade or more has done for Leeds, Sheff Wed and Forest. Talk of challenging for titles is pie in the sky I'm afraid, if Spurs haven't managed to put together a coherent challenge at any point in the last 40 years then there can be no expectation of us ever getting to that level without significant (probably impossible, now) outside investment. We don't need to be up there so that we can dream of winning the league. We need to be up there at least intermittently because otherwise you're condemning yourself to at best, mid-table second tier tedium year on year.