You don't have to, but. Sending a thank you note is a great way to let your guests and their parents know how much you and your child appreciate their effort.
I truly understand why most often thank yous are NOT sent out.
So much energy is put into planning the party and making sure everything ticks, that once it's over and the smoke has settled, all you want to do is sit back in your sofa and breath (for about a week.).
As a parent that's on the birthday circuit, I can tell you that when we DO get a thank yous it makes everyone feel great. My daughter loves it because usually thank yous have a picture from the party. And I love it because it lets me know that the effort I made was in fact acknowledged and appreciated.
Throwing a party is hard, but. So is going to parties and taking your kids to parties week after week. And that goes with mentioning the money spent on gifts, etc. Also, when we throw a party, I find it important for my daughter to take an active part in creating the thank you cards herself as a way to teach her the importance of acknowledging her friends. (Remember to mail thank you cards no later than a month after the party.) I've often seen our thank yous hanging on friends' refrigerators long after the party is over.
And lastly, you'll notice the many thank you note designs in our free printables section, just to make life a bit easier.