My experiments with React have been rewarding. I enjoy writing apps with React - it suits my way of subdividing problems into smaller modular pieces and recomposing them as a whole. The functional programming paradigm it encourages is well suited to what we do as web developers - and exposure to React and the thinking behind it has been educational and rewarding for most web developers I know. It can open opportunities.
I've been observing the React bandwagon for a while now with a view to jumping on. But utimately bandwagons are not my thing. Like the many libraries and frameworks before it, React is just one of the options out there. Right now Vue.js is a viable alternative, among the many others blooming daily, that solve similar problems. And still more will be created to solve the unique problems we have yet to encounter. Right now I'm watching Svelte • The magical disappearing UI framework.
A dominant paradigm, no matter how good it is, will not solve every problem. Sometimes the answer lies outside the popular patterns, framework or language everyone is using right now. Developers must learn to solve deeper problems and understand what lies beneath - and a job market that expects a narrow skill set will produce shallow developers.
Single framework dominance is meta-level code smell
Learn React. Use React. React is good for right now. If you're a web developer you most likely need it right now. Many freelance contracts I see now currently require and assume knowledge of React. I do think React is a genuine and worthy tool to know - but not to the exclusion of others.