You have to look at things in the long term.
In the short term, it’s certainly true that the investments are colossal for a result that’s far from guaranteed.

As for me, I’m far from having optimised things yet – I can’t really be bothered to get to grips with Excel spreadsheets at the moment – but to give you an idea, I’ve had to invest around 50–60 M, including my marketing manager’s training courses, and I reckon that in terms of profit (not turnover), I’m making about +100 K a day compared to the old system
So it’ll take me just under two years to recoup the investment.

But I reckon those who make the effort to optimise properly should be able to recoup the investment within a year. Depending on your perspective, you could say that’s either a lot or very little.

Once the investment has been recouped, if you end up making an extra 100 to 150 K in ‘profit’ per day, that’ll work out at something like +5 or 6 M per season. (But I reckon those who’ve approached it more scientifically—rather than intuitively, like me—must be making even more.)

It’s up to you to decide whether it’s worth the effort, but in any case, it’s certainly true that with the current settings (which, let’s not forget, may change), it’s not exactly Ali Baba’s cave.