RaiBlocks (XRB) - When it was first launched the dev came on here, explained how the block lattice worked and asked people to try it out. It sounded interesting so I tried it out for an evening. I netted 50,000 XRB (50 blocks, which was 'meh'). They were actually worth less than nothing back then
I checked the price of XRB on mercatox when you mention it and very surprised when the current price: 0.00078 btc/xrb. I know it and have done type captcha 1captcha / 1 mrai. I have to sell 5000mrai when the price is 1000sts/xrb. i really feel quite regret