They've been interested for a while - Stripe used to accept Bitcoin, and various Stripe employees have said they're watching developments in the space. For tha

They've been interested for a while - Stripe used to accept Bitcoin, and various Stripe employees have said they're watching developments in the space. For that matter, a number of other big tech companies (notably Apple) said they're watching the space. I think the main issue is that cryptocurrency still has a few unsolved research & regulatory problems (like how to handle more than 10 TPS, or how to record taxes transparently) before it's ready for mainstream adoption. No big company wants to take the risk that an unsolved research problem may not have a solution, and so they wait and see how the space evolves rather than committing large amounts of resources to it. (Other than FB, who has resources to burn.) If it starts taking off they'll buy a bunch of startups and then start throwing engineers at it; otherwise they risk nothing.