Worth getting into email marketing?

I am a developer and I found few very efficient ways of scraping and then analyzing users and their posts trough large social networks.

For example, it's not just grabbed email from someone that liked/commented on "dog-related" post or liked a puppy page. There would be millions of these... I can narrow it down to let's say 5k biggest, "super fans" of a certain niche.

My 3 biggest concerns:

0: I want to do mass emailing and promote affiliate/dropshipping sites but would rather not waste too much money/time. I am a pretty good developer, already making decent $$/h and not sure it's worth risking 100+ hours into this(sales copies, testing, dealing with sending emails, finishing and upgrading scrapers)... Experimenting with this could easily cost me $5-10k in lost time. I guess I could start fairly cheap by promoting affiliate sites to see what kind of stats I get. Any ideas which affiliate aggregators allow promoting their products in emails like mine?

1: How do I email these people without running into GDPR issues? These people did put their emails up publicly to be contacted... Maybe I can just send it asking for permission and delete non-responsive ones? Was anyone ever even punished for "cold" emails like this? I think I once saw a list(can't find) of GDPR enforcements and it was done like 20 times, always huge companies or govt. organizations leaking personal data.

2: I guess I would be sending 50-100k emails/month in the beginning. Will getresponse or similar companies allow me to import my lists? Or will I need to get into setting up my own SMTP stuff? (not terribly familiar, but I can probably learn fast) Any good resources here on this?

Any other ideas?

Regarding GDPR, the question isn't simple but CAN-SPAM has been there for a long time now, but things working, I know a vague answer but there isn't a simple answer to this question I think. Secondly, ESPs like Getresponse, MailChimp, etc that manages a high reputation of their sending stream keep the less flexible policy, and flexibility is something you would need in such kind of emailing. A self-hosted email marketing infrastructure can provide needed flexibility, so your own mail server can work. You can hit adnan.ahmed227 up on skype if you need a further discussion regarding infrastructure development.