I think the key words are "can be" lucrative.
Several years ago, a flipper (ex software engineer who got tired of the cooperate world) doing a project in my neighborhood told me that flipping in DFW was no longer easy.
He then stated that all the entry level, easy flips were gone- with many having been flipped two times, sometimes more. Thus, flips had gone up market with more sophisticated buyers and well funded, more sophisticated competition.
He added that marketing to more sophisticated buyers then requires higher end contractor and professional designers (designing a house that others want to buy can be hard), all of whom charge accordingly- and the needed higher end contractors can be hard to find. Projects can become money pits.
Evidently, a contractor placed a lien on one of AW's flip homes. This could indicate that not all was well with the flipping and that even cooperate level business people could face an expensive learning curve.