You can draw with a mouse, but it's genuinely harder. The main issue is that a mouse doesn't pick up pressure or tilt angle, which are crucial for painterly strokes. You either end up with a uniform line, or you have to constantly adjust brush size manually. Plus holding your hand over a mouse is tense - you get tired quickly. People drawing with a mouse usually go minimalist, do graphic work, or rely on digital filters.
If your budget is really tight, try drawing with a mouse - honestly, it might be enough for you. But if you feel like you want more control, a tablet pays for itself fast. You don't need a professional iPad with Procreate right away: there are affordable graphics tablets that work with your computer and support pressure sensitivity. With those, it's already a completely different experience.
The main thing is don't wait for perfect conditions - just start already. Draw with a mouse for a month or two, figure out the software, and you'll know whether you actually need a tablet or if it'll pass. People often overestimate how much gear matters at the beginning, but usually end up getting a tablet anyway.