When I was a young grease monkey mechanic with a serious addiction to motorcycles, due to my finances I was never able to afford more than one bike at a time. That did not prevented me from driving past motorcycle shops, stopping and drooling over the bikes.
According to Scott Bruce Duncan, MBS (multiple bike syndrome), also known as cycleholism, "is a progressive disease that scientists have yet to discover the cause of. Cycleholics exhibit an illogical, uncontrollable desire to own multiple motorcycles".
Methinks that to overcome my addiction, somebody should have done an intervention. Like a crack user get addicted to crack after the first use, I was dead hooked after my first solo ride on a motorcycle.
In the early 70's I rebuilt the engine of my 1972 Kawasaki 750 triple in my bedroom, read every motorcycle magazine I could get, and dreamed of the day when I'd have my own dragbike. Now that I am older and financially stable, one of the disadvantages of living in the city is not having enough room in the garage to park or store more than one motorcycle.
To me it is an exercise of frustration to browse through Craigslist, Ebay and Facebook Marketplace ads every week. There are so many older bikes I wouldn't mind having, bikes that can be roadworthy with simple engine repairs. Besides, motorcycle restoration is a form of therapy; well that's my story and I'm sticking to it.
In a perfect world I wouldn’t mind suffering from MBS (multiple bike syndrome), and owning multiple bikes to satisfy every riding whim I might have. The cycleholism gets worse for me when I hang out with friends who also suffer from MBS. We always attend the same vintage motorcycle events, so it is frustrating for me to hear them talk how many bikes they have and what stage of the restoring/repairing process they are in. Since I don't have the space to store multiple bikes, all I can do is imagine having my own private stable of vintage bikes, and daydream about tinkering with tools.
How many bikes are too many? I guess the best answer is, as many as you want, as many as you can afford, and as many as you have room for.