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I don't know what brand your mobile phone is or how much money you will get, since you rarely use your mobile phone, it is not a bad decision to sell your mobile phone and hold it for investment in Bitcoin. But only by thinking like this you can't increase bitcoin investment you must find an incoming source from where you can continue to invest bitcoin regularly weekly monthly then hope big bitcoin holder dream come true.
Yes it is important to have a source of income to invest in Bitcoin. Because if you don't have a source of income then you can't increase the amount of investment and may need to sell bitcoins for urgent needs. So if one wants to invest in Bitcoin then it is better to continue investing in DCA method with a small amount from his income.
However, when Op decided to invest in Bitcoin, the price of Bitcoin was much lower. If he had invested in Bitcoin then, he is now more than double in profit. OP you should try increasing your investment amount more. If you have any source of income then you can invest in DCA method. Hope you can profit a lot in the upcoming bull run.