I've been into cryptocurrencies for a while now (even when bitcoin was still below $100) I do trade as well (medium term gains) although most of my time is spent on my day job.
However, personally, I would not consider putting my retirement funds into crypto currencies. Yes I agree that it's a good investment option, and can be a regular source of income, BUT it would be unwise if 100% of your retirement fund is placed on an un-regulated, uninsured, and highly-volatile commodity. Seeing that cryptocurrencies have a bright future ahead, I'd probably consider a 50-50 split for my retirement fund. 50% on a stable market like real estate, blue-chip stocks, mutual funds and insurance plans. then 50% on cryptocurrencies. I will further break down the 50% of crypto into two parts, (1) day trading for short to medium term (2) long term trading.
That's absolutely one of the best strategies in diversifying your financial porfolio. Thanks @precise for sharing your thoughts. It somehow gave me an idea on how to further split my retirement fund properly.