For long term investment, always hodl Bitcoin is the first rule.
And then about your statement: "You must have another source of income" absolutely right. You need to create other outcomes to maintain your daily life and savings.
Don't put all eggs in the same basket. Invest in some other cryptocurrencies other than Bitcoin. Ethereum, EOS, BNB is one of these.
You're right. This market is not so easy to survive because the downtrend during the past few years is causing a lot of tired investors and some people have left this market this year. I think it is necessary to have a new investment strategy and currently Bitcoin is the safest investment that people should consider more. During this time there are not many good options for investors so it is best to just hold Bitcoin.