Interesting thought but honestly there is so many ETH miners it just seems not very believable. IF you want your transaction to go through set GWEI level very high.

Or invest in a real ICO that gives all users teh same amount of chance to buy coins at a leisurely pace and limits all users to a cap of how much they can invest in the first stages of the ICO.

Take Kyber Network for example. Properly run ICO. If an ICO allows for whale behavior just avoid them.