There is nothing wrong using the lump sum strategy if the money is there it won't trigger any financial stress if the income is available there are rich people who are using the lump sum strategy and also the DCA strategy poor people may also decide to lump sum if probably they won a lottery or unexpected huge amount of money came there way he or she may decide to lump sum without them selling there bitcoin holding since they will still be using the DCA strategy.
But it is better they use DCA than to buy at once even if the money is there. Bitcoin price always fluctuate and if we buy at once using a large money and the price is down a lot, we can be difficult to buy back Bitcoin. But if we can steady to use the same amount of money and allocate the money by our capability, that will help us to have the money and prepare for the next down time.