His profit would be 4902mBTC. Is that correct?

This is wrong.

Is it 4903mBTC?

This is correct! But: you've entered 2 answers, so I'm not sure how this counts...

Nope.

I have to go atm. Will check back later.

Is this "Nope" for retes12345, for TriggerX, or for both?

Now my answer:

Bob has wagered more than 5000 mBTC, so he has a lvl 4 account. That means his house edge is 0.94%, which gives 4903 mBTC profit.

This nicely illustrates the effect of a lower house edge. I'll show the profit for a 50 mBTC win at 1% chance for all levels:

lvl 1: 4900 mBTC (house edge 1.00%)

lvl 2: 4901 mBTC (house edge 0.98%)

lvl 3: 4902 mBTC (house edge 0.96%)

lvl 4: 4903 mBTC (house edge 0.94%)

lvl 5: 4904 mBTC (house edge 0.92%)

lvl 6: 4905 mBTC (house edge 0.90%)

lvl 7: 4906 mBTC (house edge 0.88%)

lvl 8: 4907 mBTC (house edge 0.86%)

lvl 9: 4908 mBTC (house edge 0.84%)

lvl 10: 4909 mBTC (house edge 0.82%)

lvl 11: 4910 mBTC (house edge 0.80%)