Over the whole lifetime of the game so far the profit has been around 2.042% before you take transaction fees into account, and 1.952% after deducting transaction fees.

It is mathematically 'supposed' to be 1.9% before subtracting transaction fees, so they're doing better than expected.

I don't remember the details, but the house edge has been adjusted a couple of times.  Not recently, mind you.  I think the most recent adjustment was taking the edge down from 2.0% to 1.9% when a clone site appeared which was offering a lower house edge.  It looked like Erik's way of saying "we can afford to out-compete you so don't even try".  I think before that, the house edge may have been lower than 1.9%, but I really don't remember for sure.

Your question is a little confusing.  The site pays out 1.9% less than true odds.  So in the long run you lose 1.9% of everything you bet.  Every game is effectively random, so you can't say "the profit will be 1.9% over 3 months".  You can't say for certain that the profit will ever go back down to 1.9% from its current level.  All we can say is that the average of the results obtained from a large number of trials should be close to the expected value, and will tend to become closer as more trials are performed.