Intel before Patrick P. Gelsinger only made chips for Intel. ARM doesn't make chip on the low-end and mid-tier chip, you have plenty of fabs like Global Found

Intel before Patrick P. Gelsinger only made chips for Intel. ARM doesn't make chip on the low-end and mid-tier chip, you have plenty of fabs like Global Foundries, UMC...etc. on the high end, you have Intel, TSMC, and Samsung