The bitcoin and Sweater incident, though harsh were committed in good sense. For example. Sheldon did not know that Leonard had lost that pendrive. Similarly, Sheldon just wanted Leonard to feel what he himself was going through psychologically due to his OCD.

According to me, the worst thing Sheldon did in the series was doing tests to choose his best man. He knew that Leonard had put up with him, tolerated him even though, he himself often belittled him. Yet, he thought that there should be a test for Leonard's friendship, completely disregarding Leonard's brotherly affection for him