I did a little observation in the site, and i have a question: do we are forced to buy level 2 , because the max amount the level 1 can hold is 3k satoshis, and the minimum for withdraw is 100k satoshis?
When your level 1 building reaches it's 3k capacity you need to submit a claim which is then added to your balance. This resets the building to 0 and the sats amount starts again. When your balance reaches 100K + 10K (network fee) you can withdraw the amount.
You can claim before the building reaches it's capacity if you want, but only every 10 minutes.
