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It would have been problematic if you wanted to invest in bitcoin aggressively with the money you are supposed to use to solve your expenses, but since you want to use all your discretionary income to invest in bitcoin, I don't have any problem with your decision, and it is even good for you to use all your discretionary income to frontload your bitcoin investment since you are no coiner or low coiner rather than using it to live a lavish lifestyle that will expose you to sell your bitcoin investment too early.
Let's get something straight. Discretionary income is the money left after taking care of your present financial responsibilities as at when you receive the payment. This means that you have sorted all the bills, water, light, gasoline and children's food and fees. That money which now remains is what we refer to as your discretionary income.
Discretionary income is then divided into 3 major parts but in no fixed pattern (based on your next payment) into the Emergency funds, back up funds and the investment funds. The emergency funds goes to any unforeseen circumstances like health challenge or natural disasters while the backup funds compensate for any price change within the period before your next income. You're left with your investment funds with which you can then channel into your bitcoin stash by possibly the DCA approach. This is why the discretionary income is the best source of investment funds.
Hence, investing all your discretionary income also means tampering with your emergency funds which would expose your bitcoin stash to vulnerable situations when they arise. This is just from my little knowledge about discretionary income and I know it may be of help to your prior knowledge.
No, I don't think that using your discretionary income to live a lavish lifestyle will compel you to sell too early, what actually makes you to sell prematurely is when you fall to put your emergency and reserve funds in place, and then emergency struck, that's what makes you sell too early even when it's not your intention.
Then as for the aspect of investing all your discretionary income, though it's not terribly bad, but I sees it as more problematic to you because their are so many other things you wouldn't be able to do due to the fact that you don't have the spare cash to available again. To me Bitcoin investment is something you do base on your own financial strength, not by stretching your finances that might be problematic in the future if proper money management skills is not being utilized.
Proper money management also known as Cashflow management or Financial intelligence is very important when it comes with what we use our money to do. Your Discretionary income is your hope of tomorrow after your payday. How would anyone cope after using all his discretionary income to invest?? It is assumed that on receiving your pay, you attend to your basic responsibilities first. Your life and wellbeing is also part of your responsibilities. After this, your remaining money is what we refer to as discretionary income and that's where your emergency funds and backup funds come from. You have to be clear about this terms first. Sometimes we fall victim of assumption, in that as long as we have handled our basic current responsibilities, no such emergency would arise until our next payday. This is not right as it endangers our bitcoin stash and may lead to premature sales.