Is it normal to own 3 musical keyboards?

I think you're just bragging because the question is irrelevant.

If you like them, I don't see the issue. I quit playing the violin nearly a decade ago and still have all three of mine (two were cheap student models I started out on, with one being a gift from a special person, and another was my "upgrade" when I started getting more serious about my playing; with me being the overly sentimental person I am, I couldn't part with any of them). I still have multiple bows to go with each one as well.

I rode horses for over 20 years and still have all of my tack (equipment) as well, including 9 saddles and over 40 English bridles! Even though I no longer ride, I've always found caring for the leather to be relaxing and therapeutic, and helps with the occasional feeling of missing riding that I get (and is a great reminder of my beloved horses), so I keep it all. Not to mention that most of my stuff is older and of a much higher quality than most of what is on the market today, and would be very hard to replace, so it also stays just in case I ever get back into it.

I think it's nice to have some variety as well. Even when I got my upgraded violin, I still enjoyed pulling out and playing the student models that have a much inferior quality of sound to them, just for fun. With my insane bridle collection, I just liked to switch it up for something different every now and then, because bridles have always been my favorite to collect. Same for the saddles (although part of having multiples of those was to have something to fit different horses, as well as for different styles of riding).

My father owns at least four woodwinds and a ukulele, and I've only ever seen him start to learn the ukulele. I've never seen him play any of his other instruments, even though it seems he can. He actually let me have his bamboo flute. It is a very odd instrument.