^Buying Bitcoin with lump sum is the best strategy but the problem is not everyone can afford to dump at once which is why DCAing is very effective for accumulating Bitcoin even for the retailers. And also I wouldn't say selling at high is wrong because that's the basic of making profits by selling an asset while we can't really draw the line which is high and which is low due to the highly volatile nature so all we can do is just go with the instinct and try to make best out of it.
I don't understand what you're saying.
But indeed not all Investors have a lot of money at once but that doesn't mean investors can't invest in Bitcoin because they can buy bitcoin gradually.
Of course not everyone has an Income of over $5k every month, Even many of us have an income below $1k every month. But if you have a good investment plan, Of course it's only a matter of time for them to achieve ownership of 1 bitcoin. What should be underlined is that the desire to invest must be within us.