Public VPNs are widely thought to be profitable ventures (especially for those that can consolidate lead with slick marketing) with ~60%+ profit margins. Some analysts project Public VPN industry’s CAGR (compound growth rate) at ~23% (7x growth in the next 10 years).
Ex: https://medium.com/@kolpolok/pros-and-cons-of-vpn-business-72db86b20325 (mirror).