Quite a few crusades failed to even get out of Europe. The Fourth Crusade in particular ended up sacking Constantinople after getting involved in local politics. Some got sidetracked killing Jews, pagans or rival Catholics.

No professional troops (in the modern sense) in Medieval times, but I suppose you can count the knights and mercenaries as 'professionals'. Professional armies require centralized taxation and are controlled directly by the crown. They are also uniformly equipped, organized and drilled. Feudal armies of the Middle Ages are much looser affairs; mismatched groupings of regional levies around a very tiny core of elite fighting men that may not even like each other, plus a huge assortment of camp followers and servants that do nothing but slow the march down and add to the number of mouths to feed. While a feudal army can look very impressive on account of its sheer size, its actual combat effectiveness is often rather poor when confronted with a more disciplined force. So, when you see suspiciously large troop strengths in any historical account, the esteemed and ancient chronicler may not only be inflating the figure, he may also be counting in all the noncombatants as well. Defeating 5,000 squabbling men-at-arms plus 595,000 cheerleaders and water-carriers doesn't sound quite as glamorous as defeating 600,000 glorious paragons of knightly virtue, does it?

To be fair, I don't think the Turks of Asia Minor were very united or professional at this time either. Their nucleus of fighting men was no greater than that available to the crusaders and their military organization was still basically feudal, with all its problems. The Ottoman army contained some professionals, but that comes much later and under completely different management, so to speak.