What is the ruling on earning profit from internet sites that require the user to browse advertisements in exchange for a known sum of money, with the possibility of increasing profit by attracting new subscribers or renting other users, and with an optional fee paid to increase the profit ratio and benefits?

There is no harm in free subscription and browsing permissible advertisements, nor in an affiliate bringing customers and taking a commission for that. However, upgrading membership or golden membership, and buying or leasing customers, is not permissible due to the elements of gambling and uncertainty involved.