More than once. I started on bass, it was always the instrument I was drawn to the most, but none of my guitar-playing friends were any use at writing songs. Widdling? No problem. Riffs? No, sir. After a couple of years, during which I was bassist in the school band, I bought a cheap Aria Cat from one of them and started to learn guitar. In my first real band out of school, I was the guitarist, much to my displeasure.
A few years and a few bands later, where I was bassing again, a friend and I were trying to get a band together playing what is now known as stoner, I suppose, but wasn't well established at all, back then. We were on a serious Sabbath buzz and wanted sound like Master of Reality slowed down. We tried for ages to find a drummer who would play slowly but everyone we tried either couldn't play slow or didn't want to play slow. I'm talking sub-50bpm type of slow. Zero interest, but it was the music we wanted to make at that time. Eventually, I decided to give it a go myself. I started to learn to drum and we got a bass player instead. The band folded before we really got it together but it was great fun while it lasted and I still love the music we made together. In my next two bands, I was the drummer, before getting a bass gig again.
In both cases, it was the music which drove me towards learning different instruments. If you're in a similar position, I'd say go for it. Why not? You'll learn a new instrument and you'll learn more about music, be exposed to band and musical situations you wouldn't be under current circumstances. Since those times, I been in more bands on guitar and drums than I have on bass, but I'm a better bassist because of my understanding of what the guitars and drums contribute and how they do it. These days, I live in the countryside and have room in the house set up a studio, with a fully mic'd kit, some amps, some basses and guitars and basses and I record songs from start to finish where I play everything. I'm even dabbling in keyboards. I will always see myself as a bassist first, but it makes my life a lot more interesting being not just a bassist.
Always go where the music leads you.