While players around the world want to gamble online, the reality is, for whatever reason, online gambling is not legal everywhere. And not all online casinos bother to get licensing in every possible market, as it is a long and complex process to do so.
As for 1Bet specifically, the casino’s Terms & Conditions state that access to the site is forbidden for customers, and we quote:
(a) Located within the residence of a jurisdiction that prohibits gambling
(b) A citizen of a nation or nation-state that strictly prohibits gambling.
(c) Is a citizen of the following countries or jurisdictions which collectively prohibit gambling: Bulgaria, France and its Territories, Israel, The Netherlands and its Territories, the United States, and its Territories.
Read between the lines, and there are plenty of legal places to play. But the casino basically puts the onus on you to determine that.