Need advice: do I go after job I want or one that pays much more?

Need advice on situation + navigating this job market

Here’s the situation: I just left my old toxic job and am starting a new role in a week. My old job was in buy side investing while my new one is doing finance at a fintech. However, I have been interviewing with another company that’s similar to my old one in terms of the work but the culture seems SO much better, so I am stuck. I know it’s probably not good to do what I am doing but I figured if I don’t get an offer from this company then no harm but if I do I don’t know how to proceed (it’s not like I’m doing anything illegal it just feels wrong to shop around but I’m trying to ensure I land in the spot best for me). Why Im doing this:

• The job market is scaring me and I’m terrified they’ll rescind my offer before I start -> I don’t know how to get this fear out of my head!
• I liked the work I was doing at my old company but the culture was so bad and we were so overworked and stressed that it made me chronically sick -> in back of my mind I’m thinking what if this company ends up being the same?
• The pay in the industry that my old job was in is much greater (more cushion in this scary job market) -> I know they say don’t chase this and I know I was miserable at my old job making good money so money doesn’t buy happiness but I do want to protect myself

I know that all else equal (mainly salary) I would go with the job that I already received / signed to join. I don’t know how to not let fear of being fired hold me back