A/B testing is but one way of gathering data. Also, it usually comes after the decision to actually invest in building _something_ out (even if it's only a prot

A/B testing is but one way of gathering data. Also, it usually comes after the decision to actually invest in building _something_ out (even if it's only a prototype/MVP). There are other types of data such as sizing the opportunity based on market research, competitor analysis or simply asking your customers - among many other. This shouldn't be trusted blindly either, sure. Never said that.