Does everyone prosper through development projects? Why don't all investors focus their intentions on development projects in less developed countries? Wouldn't this benefit all parties since the recipient country would be more developed and the investor would make a profit? In other words can it be said that development projects are the type of investments where no one is placed at a disadvantage and everybody prospers? ( p.s. please don't criticize if you find this is a stupid question or I sound redundant, I'm a 17 year old economics student excited to learn as much as I can)
A lot of this comes down to risk. A developing country usually don't have very strong "institution" and are much more prone to various kinds of crisis (think military coup, hyperinflation, terrorist attack, nationalization*). An investor might also not be as familiar with the developing country in question* (and hence the risk).

As a result, investors require higher return (the "premium") to invest in these countries. You can see the risk premium by country here.

This is why developing credibility could be very helpful in terms of drawing foreign investment into a country.

* Added from comments below.