Free airdrops, the ones I realised I received that made good money and especially the ones I hadn't noticed that went up 100x. The tokens I never swapped before going up 100x in value, and therefore being unable to cash in. That NFT collection that had it's data taken hostage by the web hosting, so in the end up the UI went offline, collection lost.
I've so far avoided getting scammed, but a good handful of investments have gone to 0 among others that have done incredibly well.