It's been a while since I turned my back on the possibility of working as an actor. The lack of job security is a problem when you are the sole source of income for your family. It's not going to be helpful, when the rents due, to be stuck going from audition to audition and not being in fashion right now as you've saturated the adverts or extras slots already. My logical brain said it's not worth the risks - do something else you are good at and enjoy with more likelyhood of keeping the wolf from the door. Hence, my years spent becoming the scientist I am today.
Now the reality of research science, you spend hours sending out your CV, hunting for elusive roles in areas you have skills, applying for agency jobs and trying to come over as great and not needy, while juggling writing papers and trying to source funding in your own right so you have some presence which shows you are worth employing or create your own job.
Once you get a job it's subject to funding continuing, or on small bitty contracts (I've known a 8 years postdoc Senior Research fellow stuck on 1 month contracts for 4 months) which means you never stop job hunting.
There is the same job security in the acting trade as in the sciences - only as an actor you may get enough money to see you through the dry times and while you are in a role you get to focus somewhat on the job at hand.