to be fair while i have some sympathy with the general issue of having to go up against Google in the browser market, Mozilla should have long done something to diversify their income.

On that very page they mention they have a long history of innovative products, but apart from the browser they don't really have anything that seems to generate significant revenue, with almost ~750 employees and a pretty huge budget.

That's a huge lack of imagination. If Mozilla gets a large percentage of users they will find funding one way or another.

So why haven't they done that that in the past 10 years?

Because they've had a monopoly to compete with and a very easy source of funding.

See antitrust allegations ;)

How? What does Mozilla have to sell? User data?