Want to Start 2D 3D Animation Studio
It depends on the quality you want to achieve and where your skill set is.  The bigger difference between 2d and 3d animation isn't so much the time it consumes, but rather the skill set it requires.

The techniques for both are completely different (though there is a subset of 2d animation that is based on cell-shading or other specialized rendering of 3d models).  2D animation requires good vector and hand drawing skill with generally linear shading.  It can be either very fast for basic keyframe and bend work with simple vector geometries, or it can be a painstaking manual process involving rotoscoping changes for each individual frame of animation with elaborate hand drawn textures.

Similarly, 3d can be very quick and simple when making things that don't need to be photoreal.  Textures can be more easily applied and don't have to be perfect for all contexts, lighting is far simpler to get close, though perfecting it is still very hard.  If you are doing things like 3d logo work and basic business effects (such as intro videos and some work for commercials) then you don't really need to be doing hyper realistic photoreal work and 3d animation can be pretty quick.

On the other hand, photo-realistic 3d animation is extremely painstaking, requires massive amount of processing power and a dedicated staff of specialists to get everything tweaked just right.

So, either approach can be done at a professional level with only a couple of people working on it.  Both are within the realm of what is financially viable for an individual to invest in, though 3D animation is much more expensive initially unless you start with Blender, which is free.

You should decide on which you want to approach based on what best fits your interests.  Try some 2D animation with flash, try some rotoscoped, frame by frame animation with Photoshop, try some motion graphics with After Effects and try some 3d animation with Blender.  It might also be worth getting a trial copy of Maya, SoftImage or Cinema4D if you can as well and see how you like those higher end 3d graphics packages.

Choose whichever you enjoy the most and look for work that makes use of that type of animation.