That is, while they are ‘waiting’ most of them have lost interest, sometimes because they just don’t need your service anymore. Every email you sent cements the notions that: (1) you are just another spammer that doesn’t respect their attention and (2) you can’t execute.
Very simple way to get notification. You can follow socials, or if you don't want to read any news on your feed, you can leave your email.
People are added for waitlist on their own free will. No one is forcing them to do it :)
Don't see any big problems for users here. Especially the conclusions that you can't execute. What does this have to do with anything?
Are you more likely to pick a solution that is ready now, that can solve your problem today?
For example, that was the case with Pitch.
https://miro.medium.com/max/1400/1*8k2RcO72JNlo1tYVrlRVJw.pn...
And besides, early users always get the benefits. For example, free use for a few years, or special subscription plan.
Not too bad for trying the product as one of the first.