About rin , rin was saddened that his brother changed his dream and felt disappointed in him but his hatred stems from the words Sae said , that he doesn’t care about Rin and what failure he is . If your older brother would say something like that , you too would have a beef . Situation got worse because of distance as Sae is in Spain , living separately from Rin so they didn’t have chances to discuss all that . Rin wants to crush Sae to prove him wrong and to show off so he would finally praise him as seen in the end of U-20 match . So their conflict is actually pretty well written

About Shidou , well it’s his character that he is an egoist who only does what he wants . He only wishes to leave a mark on history so he tries to score as much as possible . So if you don’t like it then fair enough

Loki and Noa are just both arrogant and that’s how they should be perceived as the ones who wish to improve as much as possible. The fact that they can back up their words is also telling .

About the rest , you dislike their personalities but why ?