My answer would be this, because there are some excellent answers in this thread. From experience i would say build your list daily, using reputable and timeless tools and focus on building relationships with that list.
Use your own membership script to do this and there are plenty of good options around, wuth my own preference being PMS by Darren, combined with Worldprofit ( Turnkey)
Build your list Build your freedom.And when you focus on being a list builder, then that is a niche on its own, with very few good people doing it
List building is the best passive income you can earn
Applied education is the Difference