Fans of every similar-sized club must surely be thinking the same thing. Just look at St Mirren - it's not that long ago they were doing better than us.
The fact that Dundee's fans on there are trapped in this "we're the bigger club" mindset is probably part of their problem. Most Scottish clubs around our level are pretty much the same in terms of size, and any could potentially do what Saints have done. Ensuring your club's future by making a stadium a priority, not over-spending on players, making good managerial appointments, keeping some consistency behind the scenes, and generally trying to do the simple things right - none of these things are rocket science, but managing to do all of them over a long term period is basically why Saints are where Saints are.
Always fascinates me why, if Dundee are supposedly such a big club in the eyes of their fans, they can't just replicate what Saints have done and be twice as successful. But they always seem to want to have some sort of sugar daddy figure at the top, and that's where things go wrong. Dundee have never been a successful club in my entire lifetime, so the idea of them as a "big club" just seems delusional (besides irrelevant). To be honest, Dundee (along with Dundee Utd) should have built a good new stadium decades ago, instead of pissing money away on players they couldn't afford, and they'd be reaping the rewards now.