I think the point OP was trying to make is that, that irrationality may not be easy to capture with automated systems, therefore the value of data is limited by your trading system/algorithm's ability to detect/predict irrational human behaviour. Or atleast that's what I read of it.

Yes, the grandparent comment makes a good point. You can have plenty of solid data and still make a losing trade.

But, given enough data-informed trades that would otherwise be proditable, the law of large numbers suggests that an overall strategy will still be sound. You can afford to have the market be irrational here and there if you really are correctly forecasting earnings in advance most of the time.

The market can stay irrational longer than you can stay solvent. Keynes.