Selling bitcoin was not a stupid decision ill think because it was your own decision to sell your bitcoin. But selling your bitcoin into a low price ill think that was the a bad decision it make. Must better to sell our bitcoins into a high price in the market cause we know profit are needed that's why we sell in high price.
Do you believe the price of Bitcoin will increase in the future or do you believe it will go down in price long term? Are there other potential investment prospects you believe will serve you better through factors such as less volatility and more predictability?
Answer at least those questions honestly for yourself and then determine if it is right for you to sell at the moment.