It can be quite painful to invest time, energy and resources into learning a language only to end up forgetting how to use it (because of lack of use). With so many fancy bells and whistles coming out of the woodwork every now and then developers ask themselves if they will be able to make constant use of a new language or framework before deciding to pick it up.
As a budding developer, your time, energy and resources are very valuable, you have to grow depth in a language or framework before transitioning into another. It might seem that you're left behind when the hype about a new language or framework comes up however you need to prioritize your learning process so as to ensure that you're able to measure your growth with more substantial metrics than number of languages learnt.