Really? If you put aside the fact that they bring in a lot of money through tourism, the Crown Estate is a massive source of funds for the public. The Crown Estate signs over all the profits to the government, in 2020 that was almost 300 million. The government then gives the Royals 15-25% back to pay for repairs to palaces, the Queen's and other Royals sovereign grants, and to pay for their staff and travel. When you consider that 75-85% of Crown Estate's profits go back to the public, that is astounding. The Crown Estate makes money from investments, renting sea beds to wind farms, etc. If the Royal family was disbanded, they would probably keep the two Duchy estates (Lancashire and Cornwall) and the government would then probably sell off the rest to businesses, so it would become private and we would only get what those businesses pay in taxes, which would be a lot less.