VPS/Dedicated server hosting and management question

I have a good deal of experience with WP and hosting companies. Most of that is building sites for small business clients where they would use shared or VPS hosting. I have a new venture for myself that involves a website that *may* see a large amount of traffic on launch. I want to plan for success (no point planning to fail). I have zero desire to manage the server (got better things to do with my time). What I want is a company that can host, manage and scale a WP site that may see a large amount of users and user content. My concerns are speed, stability, and security. I understand I will be paying more to have someone else manage but it's a headache I don't want in my life anymore. Any recommendations on solutions or approaches?