If you go warlock 2, you get 2 SP per short rest, so 6 in total, which is ONE additional fireball (3rd level spells cost 5 SP).
However, in return, you will be 2 levels behind in spell progression.
While you get fireball, other sorcerers already have a 4th level spell slot and so on...
You permanently lose spell progression!
You can absolutely not machinegun fireballs. Not more so than regular sorcerers, that is
If you take 3 levels in warlock, you get 4 SP per short rest, or 12 total. Which is 2 additional fireballs. Which yes, is more fireballs, but now you are 3!! levels behind other sorcerers.
That is anything but free
