Bitcoin should be bought and held regularly based on how much more profit it will make in the long run.
In 2016, 1 Bitcoin could be bought for $400, now it costs $112K+ to buy a Bitcoin. In the last 10 years, the price of Bitcoin has increased by hundreds of times. Now it is not possible to buy a whole Bitcoin with less money than before. But if we calculate the valuation of Bitcoin in the future, then if someone follows DCA for 4 to 10 years with less money and cannot buy the whole 1 Bitcoin, there is no problem. Because after 10 years, the value of every Satoshi he has will be several times higher. So even if he cannot buy a whole Bitcoin or a whole Bitcoin, there is no problem because after a long time, the profit will be many times higher than the investment.
None of us can ever see or say the future. So no one knows what the price of Bitcoin will be in the future. So instead of investing on leverage, first set a goal of how many Bitcoins you are willing to deposit in your portfolio. If you invest like that, you might get something good. As you said, if you invest on leverage, if you hold on to $300 and expect to get 50,000 from it 10 years from now, if you do and the price of Bitcoin does not increase as expected, then you may be disappointed and your faith in Bitcoin may be lost.
So first you need to set a goal of how many or how much money you will save in Bitcoin in your portfolio. If you go ahead like that, it will be much better for you.I understand the point you are trying to make her but I feels like the better target should be setting the numbers of bitcoin you wishes to accumulate in a particular timeframe than placing an amount, because as times passes by, the value of Bitcoin might be increasing and because it is appreciating in value, you may not even invest up to that amount you intend investing because Bitcoin might skyrocket and your target in usdt likely be breached in no distance time, and you may likely stop investing thinking that you have gotten there, but if you target is to accumulate 5 Bitcoin, you are never going to stop if you haven't gotten to your target, and it might even last for 10 years or more.