Node.js is quickly becoming a popular development platform with adoption by plenty of big and small players. One of those is PayPal, who are replacing their incumbent Java-based system with one written in Node.js. For PayPal's blog post about this, visit https://www.paypal-engineering.com/2013/11/22/node-js-at-paypal/. Other large Node.js adopters include Walmart's online e-commerce platform, LinkedIn, and eBay.
According to NodeSource, Node.js usage is growing rapidly (visit https://nodesource.com/node-by-numbers). The measures include increasing bandwidth for downloading Node.js releases, increasing activity in Node.js-related GitHub projects, and more.
It's best to not just follow the crowd because the crowd claims their software platform does cool things. Node.js does some cool things, but more important is its technical merit.