There are two main reasons why crypto casinos choose to offer no deposit bonuses to new members.
On the one hand, these online casinos must compete with a plethora of already-established casinos in a crowded industry. Just like their competitors, they must battle for new members and do so by offering players exciting offers.
The second reason is more to do with crypto itself. Crypto casinos are relatively new and there are even games on some crypto casinos that are novel. Many gamblers will not have played these games before and by offering no deposit bonuses, players can get to know them without risking losing any of their precious crypto.