In 2016, the population of India was 1.324 billion. If the government regulates online gambling and only a very small percentage of the population plays, the government will make a lot of money in taxes.
Currently, a lot of illegal gambling activity is happening in India so they are just trying to reduce that percentage and also the government can make some tax money from it. Indian government very popular for the high taxes so I expect it will be a very huge amount of tax they may add for all the winning amount and which may indirectly force people to choose to gamble illegally or go to crypto gambling sites which are not regulated for the taxes to reduct from the winning amount.
The tax should be a reasonable amount then only people may be ready to pay it because they risk their hard earned money to play these games so the government shouldn't ask for a huge amount of tax.
As you said the countries like India were asking more than the are supposed to ask that is why people are using the loop holes to avoid any taxes if they are implementing the right amount of taxes then it may encouraes the people to pay the taxes and also they can generate more revenue which can be used for country's development.
