I would argue that by putting such a high valuation on your advice, people think it's worth more, just as they have a natural tendency to think that they are getting a higher quality shirt if it is priced at $50 instead of $5.
Another point to note is that there is an incentive for all of the Y-combinator startups to say they had a good experience, because if they said otherwise they might be burning the bridges they built (which they would not want to do, even if those bridges are not worth what YC charges for them).
Another point to note is that there is an incentive for all of the Y-combinator startups to say they had a good experience, because if they said otherwise they might be burning the bridges they built (which they would not want to do, even if those bridges are not worth what YC charges for them).