If you're actually looking for make a consistent profit and have domains sales entirely support your business model (and are not just collecting domains for the future using wages and/or investment income to finance it) then this is a really tough day-to-day business to keep profitable.
And this is especially true if you're just starting out, as you can easily find yourself behind the 8-ball and without an aged portfolio to fall back on. Plus. you need to put a ton of work into it to make a profit. which is the real Catch-22 IMO.
Look at Twitter Tony (
https://twitter.com/TonyNames) I don't think he sleeps more than a few hours a night and he's always looking for a new angle to try and beat the competition.
Domain investment is a true case study on how you need to both outwork and outsmart the competition, but it's tough to equate the financial returns with the work sometimes. And no matter how smart you are, or how much time and effort you put in, domain sales have an inherent "luck factor" built right in.
I count myself as an educated and intelligent person, and I don't think there is any field I would make
less money at, with the same time investment, than in domains. That's just cold, hard fact.
But I enjoy the game and find the TBR mentally stimulating.