Why is getting my data sold bad?

My data is getting leaked all the time by all the doctor offices and whoever the fuck else who asks me to put in my address, name, phone, email. But mainly doctors cause they always want my SSN and I get at least 1 letter every 1-2 years about their oopsie because their software is trash.

Many online services are saying take it or leave it, so whatever. If I get spam calls that’s really rare for me and they wouldn’t stop even if I signed up for nothing, data brokers will get my data either way.

So, what’s the downside? I always allow websites and apps to take my cookies, to use targeted ads, to track my activity from app/browser so that they can connect those dots. I think it’s good, I’ll just get better ads, if they know what I want I’ll take a look, why not? What bad can possibly come out of me accepting all TOS vs being very picky like using open source shitty alternatives for everything, being on VPN all the time, using privacy-first shitty devices instead of apple/samsung/google/lg/etc?