> I think landowners in the Roman Empire did in fact partake in other business, say starting gladiator companies.
I think it somewhat depends on the era, but in general if you were a senatorial family, you wouldn't want to do this, because you'd lose your senate seat (and might face other sanctions from the Censor). There were rich non-senatorial-class people, some of whom would have been much richer than most of the senators who might own land along with other stuff, but the big landowners were generally the senators, because they weren't allowed do much else. I think even, say, building an apartment block on land they owned was dubious territory for a senator. Mercantile activities were right out.
In the English case, the landowning classes generally didn't invest in non-land things, and arguably the trigger of the industrial revolution was less the technological advances, and more the development of the capital infrastructure to invest in using them (banks, joint stock companies, etc).
I think it somewhat depends on the era, but in general if you were a senatorial family, you wouldn't want to do this, because you'd lose your senate seat (and might face other sanctions from the Censor). There were rich non-senatorial-class people, some of whom would have been much richer than most of the senators who might own land along with other stuff, but the big landowners were generally the senators, because they weren't allowed do much else. I think even, say, building an apartment block on land they owned was dubious territory for a senator. Mercantile activities were right out.
In the English case, the landowning classes generally didn't invest in non-land things, and arguably the trigger of the industrial revolution was less the technological advances, and more the development of the capital infrastructure to invest in using them (banks, joint stock companies, etc).