After a month of trial and error, I've finally found a solution!
How to remap Middle mouse button something else? If you don't have a three-button mouse, this is a must-have for blender (esp. Laptop)
I'm aware of "emulate 3 button mouse" in Preference>>Input. But if you check that option then you won't be able to 'Select loop' which uses ALT leftClick.
What if you could remap Mbutton to any other key you rarely use? Yes you can!