G-RICH
No, it doesn't really apply - we'd just strayed from Norman2's question to the wider issues of who airlines recruit and why. It's a topic that's been moot on a number of threads recently. I apologise to Norman for getting off-topic - which, to answer your points, I'm going to have to do again. Sorry!
You're right - the greatest training risk is the inintial entrant to training. There's no history, so all the employer can do is ensure that the candidate has a majority of the physical and mental characteristics of those who have succeeded in the past. As this is, at best, an imprecise science, many of those candidates will fall by the wayside until, at the end of line training on the first commercial (or military) type, you have a pilot who you can reasonably expect to succeed through the rest of his or her flying career. When that pilot is required, in later life, to undergo training on other types, their proven aptitude combined with their growing experience will make such conversions relatively straightforward and risk-free.
Those under-30s whose lives primarily revolve around booze, 'music', and the opposite sex are unlikely ever to succeed in this process, as you suggest. Er.... on the other hand, that description fits a great many pilots I know - including me and one or two other Mods!! But determination, confidence and motivation are certainly the most important qualities for any wannabe.
The trouble is that learning a completely new skill gets progressively more difficult as we get older, so we need more time to successfully master it. Employers, of any variety, are reluctant to indulge in extended (ie more expensive) courses to accommodate older trainees, and so they tend not to offer them - and they certainly won't queue to train untried pilots of relatively advanced years! That doesn't mean that it can't or won't happen for Norman2, just that it's less likely than for someone 10 or 15 years younger.
As for your advice about keeping a second string to your bow, I think that applies to all of us, doesn't it?!