Samsung at its peak, circa 2013, made $9.6B operating profit on $55B revenue. Samsung's gross sales revenue, profit (and margin) in mobile has been steadily declining since.
The Mobile division's 2Q 2012 profit was less than 10% ($1.95B OP on $20B revenue). Then Trump's sanction of Huawei happened, after which Samsung's sales grew by 50% QoQ (3Q), but we don't expect Samsung's luck to last forever and their margin would start declining to a mid-single digit again.
Yeah, Samsung doesn't restrict itself to lucrative industries. So many of its ventures are in markets where marginal cost ≈ marginal revenue, and they're big enough and competent enough to get rich doing so.
The smartphone business is maybe not the best example though, since the brand reputation that having the second biggest name in smartphones confers surely pays dividends across their consumer product lines.
While app store is more or less required for a phone to sell, those devices still do that quite nice margins. There’s no third party game store you coukd use on a console (apart from steam big picture).
Samsung has let Google make the money.