Most companies pick processors on the market rather than in-house because they can’t afford to divert money to boost processors. Instead, they spend that money to build up the customer base effectively.
Even if they are profitable in developing one, the performance would generally be unsatisfactory to lack of journey in the field.
Samsung, Huawei, and Apple boost their personal processors Exynos, Kirin, and the renowned A-series. Because they should find the money for the R&D charges and are ready to make more than a thousand to improve their products. In return, they decrease the fee of producing processors compared to buying them from groups like Qualcomm and Mediatek in the market. They sell them after having their share of income from it, increasing the fee of the product.