Investments are made for a lot of reasons but most of them dont apply to Football clubs. Growth by acquisition, taking out a competitor etc, getting market access etc. The problem Jezza has, is that as an investment (i.e growth to a prem club and the glories of Sky money) he has milked the club dry. He will walk away from any eventual sale better than any future owner will (and has done a great job imo so I don't begrudge him).
How do you buy us for £40 million and make money? Wages run at such a high percentage of turnover that if you want to keep us in the prem and make the sky money you cannot just stop us spending, we would go down. Asset strip is the only way. Take the 90m and sell off the squad. Nobody can come in, pay £40m and take us to the next step, and make money. We aren't big enough, merchandise and ticket sales will never be a gold mine.
We don't need an investor, we need to be someones play thing, and that can go either way.
That is why he struggles to sell.