Beginners arena bracket grind

Hii. I’m new to the game and struggling with Arena grind. I’m in the beginners bracket and for the basic 3* arena, I’ll probably need about 1.5 mil points (Estimated from a post on here about beginners arena cut from January 2020). How do I even rack up that much points? I do basic 3* arena re-runs about 8-10 times a day but can only rack up 200-240k points at the end of each day. I have about seven 4* heroes and would want to put my resources there (well at least till I get a 5 star) so none of my 1, 2 and 3 star heroes have been ranked nor levelled up. Because of this, I cannot have infinity win streak as these heroes are quite low. In one run using my entire 2 and 3 star heroes, I could rack up about 20-25k points before I loose a match and start the streak again after the cool down time. Doing this 10 times a day (Character Cool down period of about 2hrs between each run) means i must have used up 20 hrs from the day. I only have 4 hrs to sleep. With this, I’ll get about 200-250k points for the day. In 3 days, I’ll have a total of 600-750k points. How then am I supposed to get 1.5m which could be slightly over 2 times my final score so that I could get the hero and grow my rooster. Now i’m certain that i’m in the beginners arena, not veteran because i’ve checked leader board and also, top rank says 1-50 not 1-200 which is for intermediate nor 1-800 which is for veteran. And this is me just focusing on one arena whilst there are two 3 star arenas. I’ve still gotta think about the 4 star arenas.

Am I grinding wrong? Is there something wrong i’m doing? Something i’m not doing but supposed to be doing? How exactly do you grind? I look forward to your responses.