Depending on the staffing and the situation at any particular airline, MANY pilots intentionally bid Reserve, myself included.
First off I know you’re eager and anxious to get your hands on a jet, and don’t misunderstand, after 15yrs I still LOVE my job. BUT, in time you may come to realize the only thing better than getting paid to fly an airplane is getting paid to NOT fly an airplane. Think about it, if the airline is properly staffed and they know all the flights they have every day, all they have to do is build schedules and cover all the trips. Easy and done. The reason for Reserves is exactly that. To be in reserve. Reserve pilots are extra pilots to be used in the event of abnormalities (someone calls in sick, a plane and crew gets stuck somewhere for weather or maintenance, etc). If you’re airline has good maintenance (which most do) and your pilots are healthy (which most are) there really isn’t generally a great need for extra pilots. Now regardless of whether you’re a lineholder or reserve all pilots get paid a minimum monthly guarantee (usually around 75hrs). You get paid that 75hrs whether you fly 0hrs or 75hrs, doesn’t make a difference. So the question becomes would you rather get paid 75hrs to fly a regular schedule OR 75hrs to stay home with the family and friends?
Now of course there are a few caveats. First of all Reserve stinks if you commute. Nothing worse than having to fly 2 legs to get to work only to sit there waiting for a call that never comes and having to pay for a hotel or crashpad. I don’t commute. In fact I’ve never lived more than 30 min from the airport. All airlines have Reserve call min notification times (there’s usually long and short call. Long is 12hrs notice, short 2 or 3). 12hrs is easy but even if it’s only 2, I keep a shirt ironed and a bag packed and I go about my business.
Next there are times when the airline isn’t properly staffed (bad weather for days causing rolling delays and cancelations, new destinations or added segments, etc). As a Reserve you’ll get called first and possibly often, get your days off canceled, get your duty times pushed to the legal limit. Getting paid to do nothing sometimes comes at a price. There are generally far less protections as to how you can be used and sometimes it stings.
Finally if you really want to fly, either because you just like or want to make more money, Reserve pilots have less ability to pick up trips or enhance their schedules. Also many pilots simply want to know where they’re going when and with who. Like anything else it’s a choice (unless you’re junior and get assigned it). For me it works out really well. I usually fly about 30-40hrs a month and if one of those trips comes on a day I had off that gets added on top so I’ll be getting paid 80-85hrs for only flying 40 (its like double-time) and end up with many more days off in a month. For me it’s a great deal.