A bail is used as a means to make sure you show back up to your court appearances after they release you from jail on the bail.
So if you post a cash bail from your own money without the use of a bail bondsman then if you show up for court and make all court appearances you'll get your full amount of bail money back whether you're found to be guilty or not.
If you don't show up for all court appearances then you won't get the money back.
If you use a bail bondsman you'll still have to pay the bondsman there money and you'll be out the money whether you go to court or not.