Usually here on Massdrop there are drop tiers.
The more people interested in a product, the lower Massdrop can purchase the items in bulk.
You commit to join if**/when the drop reaches it's lowest price possible.
**If it does not reach the lowest price then the drop was unsuccessful. Which also means the people that commited to join at the lowest drop price will have the orders cancelled, sense it didn't reach the said price.