Has the long-term direction of the markets been up or down? If up, then lump sum will win on average. If down, then DCA will win on average.
Some people will DCA as a way to better deal emotionally with the turmoil of the markets. I think that you should just have a proper asset allocation to handle that.
Your bigger issue is your apparent unwillingness to invest.
64k in cash, and 700 in the market?
Your current liquid asset allocation (ignoring debt ) is 98% cash, 1% stocks, 1% bitcoin. Not a proper asset allocation for someone who wants long term growth, or really just about anyone in any situation. If you lump sum invested $6k into a stock mutual fund, you'd be at 10% stocks, 1% bitcoin, and 89% cash, which is still way too conservative. DCA should be out of the question, IMO, and you should really be looking into putting your other capital to work.
If you're not very comfortable investing, I'd suggest something like a balanced 60/40 fund like VBIAX or VSMGX at Vanguard, keeping only as much cash as you need.
Finally, it makes little sense to be earning 1-2% on 64k in cash, less after taxes, while paying 3.8% on $13,500.