I am pretty sure they included backers in that 600k. And "tens of thousands new users since 1.0 release" sounds pretty bad. That's why they ask for reviews, game underperformed and they need more sales. Also, a big chunk of these "tens of thousands" bought the game on sale for half the price. My guess is since 1.0 release they made 100k or less, but if someone wants to make more educated guess by estimating purchases based on purchase to review ratio, be my guest.
We can see exactly how many people backed since the Kickstarter is public data. It's 60k. So 540k in actual sales.
Let's assume average buyin was $30, since it was $30 for most of it's life and it's a good middle ground from the 1.0 price and the current sale price. 30x540k is $16-17 million. Add in the $2mil they made off the Kickstarter and it's about $18-$19 million in total revenue.
Dev team seems to be roughly about 14 people, 1 of which was just a contractor for the art. Another 9 or so are animators/artists/VAs that'd get paid by what they produced. Salaries even for the time it took to make the game can't have been that incredibly high.
Even if this "flopped" at 1.0, it was still a resounding success. $20 million isn't great for a major AAA studio, but it's pretty solid for a dev team of basically 4 people and several contractors. Even if they pumped a considerable amount of that back into the game, they still probably walk away with a warchest of several million to split between a relatively small group of people.