Actually $150k a year is the absolute minimum that they make, which is why I wrote $150,000+ a year, because they are definitely making more than $150k. Look at their patreon and the lowest tier you'll see is $10, that's the minimum that you have to pledge to get the game. Also if you look at their statistics their average patreon pledges $10.
2000 patrons * $10.00 * 12 months = $240,000
After Patreon takes their 5% and taxes (if they even have to pay taxes on it) they're likely making $200,000 a year.
graphtreon page