Why don't they simply give it up?
Because hopefully Microsoft will not be able to get away with using anti-competitive practices to crush rival browser products.
They used their tried-and-true tactics to nuke Netscape and many other Enemies of Gates.
1. Buy #1 competitor to the Enemy's Product.
2. Repackage competitor's product.
3. Repeatedly release versions of Windows/DirectX which are designed to make Enemy's Product incompatible with Windows, causing:
a: Consumer dissatisfaction with Enemy's Product and subsequent loss of market share.
b: Enemy is forced to spend enormous amounts of programming effort just make their product usable after each new Windows/DX release.
c: The programming effort sucks up money and forces programmers to spend time fixing "bugs" instead of adding features.
d: The lack of new features decreases the "feature gap" between the Enemy Product and the Repackaged MS Product, eventually resulting in the MS Product becoming superior.
4. Give repackaged MS product away for free, forcing Enemy to follow suit in order to compete for market share.
5. Loss of revenues from 3a, 3d, and 4, plus increased expenses from 3b and 3c causes Enemy to implode.
They did this to Netscape and Roger Wilco and a few others.
But homey ain't playin that toejam no mo! At least not if the DoJ keep their heads out of their asses.