Used to be vehemently against using a pick when I first started playing, mainly because that was the ONLY thing bassists in my high school were doing. A lot of them were the guitarists who were like "Oh man this is easy!" and all they did was playing straight 8ths on the E string. So it actually took me a while to get over the whole "pick hatred". Guys like Justin Chancellor and Chris Squire gave me more respect for pick players. When I got older, people like Carol Kaye would come onto my radar and further cement that using a pick can be done well and is a good technique to acquire.
Since I played guitar as well, it didn't seem that alien to me until I started doing some string skipping and quick transitions between strings. The spacing threw me off, but now I have difficulty arpeggiating on a guitar, while bass is pretty natural for me. It takes some concentration to play a song I "know" on pick with my fingers only, but with a little focus it's doable pretty quick. Just pick some songs that are originally on a pick and practice those until you get comfy, then try playing songs you knew how to pluck and play those with a pick. If you don't mind their music, Strutter by KISS is a pretty fun bassline that I use to warm up my pick playing.
Since I played guitar as well, it didn't seem that alien to me until I started doing some string skipping and quick transitions between strings. The spacing threw me off, but now I have difficulty arpeggiating on a guitar, while bass is pretty natural for me. It takes some concentration to play a song I "know" on pick with my fingers only, but with a little focus it's doable pretty quick. Just pick some songs that are originally on a pick and practice those until you get comfy, then try playing songs you knew how to pluck and play those with a pick. If you don't mind their music, Strutter by KISS is a pretty fun bassline that I use to warm up my pick playing.