Presale is a very good way of making profits for investors because they are likely to purchase the token at lower price, always lesser than listing price, and when the token is listed successfully... it's a mega profit making, but we see different projects sometimes are unable to meet up hardcap or even softcap at presale and making listing impossible. Investors are likely to run on loss because they don't possibly refund them when project isn't successful.
That's not true about the listing price will always be higher, no doubt when the tokens get listed the price candles make big moves but a pre-sale buyer might not be able to sell them that high due to order book delay or liquidity problems. There could be any problem, and there are tokens that got lower than the presale price, and the investors made big losses. But it happens rarely in legit projects.
Mega profit is not confirmed because a person might consider 2x a mega profit but for another, it won't be so please justify what's the definition of mega profit in your terms.
You are right, a refund is not possible but if you are talking about centralized exchanges from the tier 1 list then you will get a full refund if a project fails to meet soft or hard cap and which results in failure of listing.