When words of thanks are missed, it leaves one feeling taken for granted. I'm an advocate of offering thanks to all for any support, as it encourages repeat involvement with you again. If I help someone and they neglect to show their appreciation, I am hurt, it does side swipe me. I'll be cautious to offer help the next time, but I will assist and tell myself it was an oversight on their part. But if appreciation is not shown a second time, I'll find an opportunity to discuss it with them, even if it's to talk about the benefits of praise.