Yes, it's safe to use a VPN to play at PokerStars, 888poker, GGPoker, and other online poker websites.

Terms and conditions of poker sites disallow the use of VPNs for the purpose of grinding while in a restricted country, but the sites have no issues with regular grinders taking advantage of the vital security benefit provided by another layer of encryption.

Yes, it is legal to use a VPN to play at PokerStars if online poker is allowed in your country. However, keep in mind that VPN usage doesn't make an illegal activity into a legal one. So, if you live in a region where gambling is extremely frowned upon, you might still get into trouble.