We have to bear in mind that they probably already have €111m of Lautaro money burning a hole in their pocket.
Look, it's plainly obvious that it's much easier to improve a failing team by adding an improved transfer budget and good players each season. We don't have to look very far to know that. It doesn't mean that it always works - it needs competent people in charge, and Marotta certainly is that.
If Marotta had peanuts to work with he'd face the same limitations of any DS. He's a talented DF/DS, but it's just as big a factor that Inter are now bankrolled by Suning. Their net spend for 19/20 was over €100m, plus taking on the salaries of players like Lukaku and Eriksen.
Since Suning took over four years ago at Inter their NET spend (fees) is just over €300m, so a decent scudetto challenge is exactly where they should be. It's only the overachieving of Lazio that is stopping them from being 2nd. Even with a slew of sponsors stepping away from the club from next season, they'll fill them with Chinese and other global replacements. Marotta has seen two years of this with about 20% growth in turnover each season.
Going straight in for Conte was a fairly easy and maybe somewhat of a guarantee as a choice, that at least the club would be competitive. When Conte was brought to Juve by Marotta and Agnelli it was a significant gamble, based on passion and history.