Venice needs to have a larger native population to keep its 'Empire da Mar' alive and strong for much longer. To garrison Egypt would probably require Venice to control most of northern Italy, or at least some of the major cities like Milan, so that it can have a bigger loyal population willing to serve it. Of course there's always the mercenary option, but that's not always cost effective.
To capture Egypt, Venice has to move before the Ottomans, who defeated the Mameluks in 1516-17. From about 1500 onwards Venice was usually on the defensive against Ottoman expansion, and I doubt it would have been in a position to successfully attack an Egypt already under Ottoman rule in the mid 1500s. If they can get established in the late 1400s, they might be able to mount a successful defence of the country, depending on the effort the Ottomans put in. Ideally, Spain will be willing to help with naval support, as Venice may not be able to hold on alone against a determined invasion force.