The Era of sticking to just a single career has really passed or becoming outdated especially in this present age and time, gone where those days when they eyes hasn't really open to things, less bills and stable economy, back then people once they have a career will make sure they stick to it because they believe if they stick to the career there are lot of benefit attached to it like stability, having more deeper knowledge and expertise on the career they choose which will usher in more sense of mastery, it give them full focus in laying down their solid foundation without any side gigs to act as distraction, back then if you see a teacher or professor, he will never do any other work than the teacher or professor work, he will finding every means to further in his studies till he reach the master level, have seen people like that back in my secondary school days.
But truth be told, things have really change nowadays, people rarely focus on just a single career, we now diversify into different things because that career you even choose is like a tree that has lot of branches and to become a master you have to know those branches also, it is like bordering your skills and knowledge. There is this Adage that says "Jack of all trades is a master of none", this is what actually stick with us and anytime people see someone doing different things/skills, they will start calling him jack of all trades but they didn't finished the whole adage which says "A jack of all trades is a master of none, but oftentimes better than a master of one".
Let take Programming as an example which is one of the modern days skills, someone willing to be a skilled web developer will have to diversify into various things like learning different languages from html to css and javascript, then he still need to learn Node Js, React and other languages, yet when applying for jobs, they will still want him to have skills in some other languages or even Ui/Ux basic skills, now imagine he is just a single career person with just a single language skill, he will look like an half baked bread, same as graphics designer, data analyst etc.
If I'm to choose, I will rather be a multiple career person that just a single career person, I have the chance to be exposed to various industries and also different skills, if one skills isn't working at the moment, I will go for the next, now that remote jobs are everywhere, you can easily engage in 2-3 works diligently right from your home. While at that, you also build up your creativity skills and also be good when it come to solving problems. Well people do run away because of some disadvantages attached to it like being emotionally stressed and reaching the burnout limit due to lot of works at your disposal, doing different stuffs at a time can really be exhausting and people get tired of it easily but as long as the bucks is worth the stress, I don't mind, also you won't be that stable and you have to learn different things continuously but still Multiple careers all the way