Many people can benefit from your knowledge, experience and even...opinions. If you are friendly, truthful and put some thought into answering the questions that people ask, you will have earned whatever thanks you get.
A lot of people are just looking for some rationale for making a decision on some issue or another. Some will base it on numbers and specs, others by the experience of veteran members. Some others may rely more on the opinions of certain posters to make their decision. So if you have a relevant comment to make that you think might be useful, don't be shy. Post up. And relax, too. If you make a mistake, it will surely be caught, corrected and more learning will be had by all.