If you want to become a crypto-currency software developer you need a lot of knowledge in software development. Like other jobs, you need to be professional and skilled in your field. It's base on knowledge because how can you do well in software development if your knowledge is not enough.
Knowledge can be gained through daily practice and time is actually needed less than it initially seems. It's all about diligence and daily practice. Now there are a huge number of lessons on YouTube, through which you can get almost any secondary level education.
Unfortunately, developing Cryptocurrency is not that easy. Yes, we can lots of lesson from YouTube but that would mean you need to have all the necessary knowledge before understanding it. You also need to have a creative mind that would need to be converted digitally through critical thinking and programming. Developing Cryptocurrencies does not mean you will dive right into programming BUT learning about Blockchain Technology is the thing to keep in mind. Cryptocurrencies are always integrated with Blockchain thus having its high level of security. You could actually learn about Blockchain before diving into Cryptocurrencies since Blockchain is not all about Cryptocurrencies.
What you should have in your daily time is spending time around Blockchains and see what more they can do.