Well I did it in the past and I've seen someone who did it too but used it differently:
1 - the one I know : they scraped millions of emails , and turned that into a lead generation SaaS business charging people around 10$/ per 10K emails per month (something like this), they got their initial users from websites like Appsumo offering lifetime access or big discounts also getting listed on appsumo will generate some traffic to your SaaS.
2 - My Case : I have a youtube channel in which I m already offering a ton of value and I know that anyone who will find out about it will subscribe 100% (no one is doing what i m doing in my niche), so I scraped like 20K emails, sent them a cold email just presenting my channel and what I do and was able to convert that to like 1K subs in just two or 3 days, on the long term some of those will end up paying for one of my services for sure.
Think out of the box.