It's a trade-off. It depends on the level of quality that you want.
You can easily render "movies" on one computer, even a laptop. I personally haven't delved very deeply into Blender, but I haven't created anything that took more than, say, 5 seconds per frame to render (using the default Blender Internal engine). At that speed, at 24 FPS, it will take you 2 minutes to render one frame of video. If you decrease the resolution, or render at 12 FPS, you could get it down to 30 seconds per second (but the quality will certainly not be as good).
In tools other than Blender, you can render movies in real time (1 second per second), or even faster. That is what a 3D video game does, after all. But it will not be professional movie quality.
Huge movie studios have huge teams of artists and programmers trying every trick they can think of to make their movies look professional. For them, realism is more important than cost and rendering time. Therefore, they end up with movies that look very real, but are really really really slow to render. Then, they buy tons of hardware so they can render it anyway.
If you're rendering on your PC, you would probably choose to make a movie that renders much faster, but doesn't look as good. You might not have the time to make it perfect, anyway - you're only one person.
Note that rendering is quite flexible. To get very quick feedback, you might render individual frames at a low resolution (like 320x200). You could preview sections of your movie at 12 FPS, by skipping 4 out of every 5 frames if it's meant for 60 FPS.
Then when you're absolutely finished, you can crank the knobs to 11, render in 4k 60FPS and let your computer chug away for two months. Or choose 1080p 30FPS instead, and have it done in two weeks. Of course, "two months" and "two weeks" are just examples - I don't know how long your movie will take to fully render.
If you find a small mistake in this final render, you can fix it and re-render those specific frames. If you find a big mistake when it's only halfway done, you can stop it, fix the mistake and render the second half. You don't need to wait for it to finish - you can let the computer work around your schedule. It's not like you have to start it going and then leave your computer on 24/7, and start all over again if there's a power cut. If your computer fan is too noisy to sleep with, you could do a chunk of rendering every day when you're at work, and stop it when you go to bed, and so on. (Note: this depends on the output format. For maximum flexibility, you want to save every frame as a separate picture, and then put them together into a video file once all the pictures are done)