Perhaps it would be better to say that they deserve thanks, but you also have to take into account the time in which these donations happened - which was mostly at a time when the price of BTC was very low, and people were mining with their computers and for each block received as much as 50 BTC reward.
True, the price was low at the time, but it was still a valuable item, and given the buzz and promise of bitcoin, everyone knew that in a few years it would be more valuable and in high demand, yet these people had the courage to donate to the forum. Even if the price was so low or if they mined and obtained BTC for free, it takes a brave mind to donate as much as 50 BTC. They still deserve to be appreciated because they made these donations for the benefit of the forum, demonstrating how much they care about and support the bitcoin community.