I also sold many of my Steem Monsters/Splinterlands cards, but not all of them. I still play the game sometimes, and I receive both daily reward cards and season end reward cards. Both of these can be sold, and then can be converted to Steem (if the cards are not bought by Steem), and the Steem could be powered up. Congratulations on your successful tipU token trading! I also sold some Steem Engine tokens, but I have not tried trading on the Steem Engine so far. Maybe later. From your example, if we catch the volatility at the right time, then we can make profit. Sometimes huge profit. I heard about someone, who made (around or more than) 500 Steem by trading with SteemLeo on the Steem Engine.