We've built web applications based on Django for small CMS sites, large multi-language CMS sites, up to large custom-built applications (mostly API-based) for the likes of Mercedes-Benz and Deutsche Bahn. I can honestly say that I never regretted the decision.
It scales beautifully (see the likes of Instagram, Disqus, Sentry, etc.), has a great security track record, sane deprecation schedules, and the core team keeps up with the times and new technologies but does so at a sane pace and without rushing things.
Not to mention the documentation - ohmygod, the documentation!
In a nutshell: pick Django, keep learning Python, and try to build something that your users love.