You only mine blocks on top of your previous blocks, ignoring blocks produced by the 49%. Since you have 51%, your chain is the longest over time, so you have 1

You only mine blocks on top of your previous blocks, ignoring blocks produced by the 49%. Since you have 51%, your chain is the longest over time, so you have 100% of the mining rewards. You can't do that with 25% (or even 40%) hashrate.