Ahahah no.

If I was a malicious miner and I found a block, and I would make 25 BTC + fees from publishing the block (so around 28 BTC?), I could bet on your site for a few hundred BTC and make it +EV.

Miner can choose to not broadcast mined blocks if the block hash would make them lose. This doesn't guarantee that they will win (as another miner will probably find and broadcast the next block hash), but it shifts the odds enough in their favor so that they can make a profit.