I don't think it will illegal.
To start a betting or lottery business, one must initially have a gambling license so if the business does not have a license to operate a crypto based gambling business, then the whole this is illegal.
Offline gambling will always need a licence and most of the countries will not issue a licence. Mostly government will not encourage their people to gamble and lose their money.
Usually this online gambling using bitcoin is not illegal as long as you do are not required to comply with the KYC
since that will make you safe not to be trace, actually it's easy to change your IP address so even if there are sites blocking an IP of a certain countries
you can still play and enjoy.
Bitcoin gambling is fair enough to consider not illegal, there are casinos which really registered and have papers for operation. It will only be illegal if crypto and gambling were totally banned in your country. And Governments will be needing a good cybersecurity to really detect those who are not complying for there are many ways to still use it even its illegal.