Its worth the risk IMO. Firstly, the depreciation on a vintage TT is way, way less than on a new belt drive TT. You also get a piece of history as well as a functional HiFi component .
Going through life in fear of something breaking down is no way to exist. Look at the stats - chances are things won't go wrong anyway, so why choose to fret about it? You can always buy a spare if you really cant sleep at night.
Long term the vintage DD will be cheaper. Many high end belt drive TT's I can think of have an uber expensive upgrade path that give you the feeling you are missing out unless you keep spending. Not so with some of the substantial and dare I say majestic DD turntables ( in terms of engineering and appearance).
This may not be an advantage for everyone but chances are the wife can probably handle a vintage DD TT more so than the less ergonomic belt drives. And both of you don't need to go cross-eyed every night trying to take a reading from a strobe disc........