Fame's a fickle thing. Many people manage to stay famous their entire working life; some by re-inventing themselves (Bowie), others merely by the fact that we can't really forget about them, no matter how hard we try (Princess Diana, and yes, I know she's dead, though I also suspect that most Mail readers think about her many times daily).
Fame comes late for some people; what did Richard Wilson or Thora Hird do before they were 60? Others find that fame comes to them early, and then leaves them just as quick; note the cautionary tale of Macauley Culkin, or Corey Haim (or was it Feldman?). There seems to be a real problem with over-exposure, and never was this more true than in the 1980s. The 80s spawned the Hollywood brat-pack, who churned out film after film in the latter part of the decade; then the decade ended, and the curtain came down on the career of Ringwald, McCarthy, Nelson and the twin Coreys. Incidentally, lest you think that this happened only in America, and only to glamorous people, the very same fate befel the 'never-sure-why-you-were' popular Tony Slattery. His brylcreemed side-parting and lavicious grin were rarely far from our screens, and then...nothing: he'd been whisked away as we heralded in a new decade.
Of course much of this instant fame followed by an similarly instant fall from grace is more about our inability to stick with something and our low boredom threshold than it's to do with any lack of talent on the part of the performer. We also don't like to see people at the top for too long (Kevin Costner), and we get bored of the same old face beaming out at us for too long. Some folk do have an uncrushable longevity about them (Forsythe - unfathomable, or Monkhouse - a legend), but most people come and go as we build them up just to sweep them back under the carpet.
And this is what I see immimently about to happen to David Mitchell. Maybe I've just been unlucky, but he does seem to be everywhere. What started out as a comedy actor playing a lead role in a funny original sit-com has now become: flogging said sit-com long since it went over the hill, writing an Observer Column, appearing on almost any panel show going and hosting a raft of 10pm-ish moderately watchable nothingish comedy gameshows that seem perfect for the 'it's not time to go to bed but I have nothing else to do' slot. He was undoubtedly funny in peep show (series 1-5), but that was largely because he was playing himself, and we identified with him; his vulnerability and insecurities were there for us all to see, and they were funny whilst at the same time making us feel better about ourselves. Now though he's gained confidence, and he's starting to take the piss out of other people. Surely this shouldn't be allowed; and we're giving him just the platform from which to do it, with his column, new-found presenting skills and occasional one-liners on mock the week.
Can it last? History is against DM, and my advice is not to over-expose. Get back to playing yourself in sit-coms, written by other people, and we promise to laugh, and mostly with you. Otherwise, you'll end up like Slattery. I wiki'd Tony S just now, to see what he's been up to in the last 5 years. Here's the sum total:
In January 2010, he appeared with Phyllida Law on Ready Steady Cook.
The future's not bright.