The issue there is time. The Nobel prizes will be announced in around 9 months. Buying a share of "No" would currently cost 98.2 cents, working out to a (basically) risk-free return of around 2.4%. Alternatively someone who wants a very low-risk investment product could just buy 1-year t-bills with a return of... ~3.5%. And that doesn't require messing around with buying crypto and the inherent risk of trusting Polymarket with your money.

Anything under 3%/year of time until decision is going to have pretty limited predictive value within that range. Anything starting above that range will end up hitting that floor rather than going to zero because of the difficulty of finding a counterparty.