Very astute question. That's the reason the proof-of-work function has to be "progress-free". Each time the miner performs a hash and finds an insufficient valu

Very astute question. That's the reason the proof-of-work function has to be "progress-free". Each time the miner performs a hash and finds an insufficient value, they are no closer to finding a block than when they started. Each hash has a liklihood of being a solution of approximately 1 / (difficulty * 2^32), but is also a a truly random lottery. Finding a trillion bad hashes doesn't make you next hash any more or less likely to be the solution.