You can buy an NFL franchise in Jacksonville because there is cost (and to a large extent revenue) certainty. Can't say the same about buying an English football club. Just the opposite. I don't necessarily disagree with most of the rest of it, but there seems to be more than just idle chatter that the NFL wants a team in London. If he positions himself as the person to do that, he'll be in a very envious position.
Oh he absolutely wants to move the Jags to London. He's practically out in the open about that. So he may think having a London football team might help (but really if Roman brought an NFL team to London would Spurs and Arsenal fans think "oh good local boy Roman has an NFL team now ... I will support them and help him out"). Getting involved in local rivalries could hurt his NFL teams chances for fan support as much as help them.
Plus I'm not sure how many people will envy the ten years he spends in London before the team moves back to the US.

Good chance NFL in London will be a poisoned chalice just like it has been in LA.
Of course a big chunk of that could be the higher ticket prices London folks can stomach (the most expensive ticket is 3x what ours is), but also the corporate income they get. A whole lot more companies are based in London than in Liverpool, so getting a slice of that pie must be easier.
True that is certainly a factor. However it's still going to be a fraction of what the likes of Arsenal generate. If you can't get a box for the big three London teams how much money/interest is left for Fulham tickets? West Ham will probably get the lion's share of the "leftovers" with their new stadium. I have no doubt they'll generate more money ... not sure it's enough to make up for the fact that you are starting with a worse team with worse infrastructure (our elite academy etc.) and competing in a market with 3 CL quality teams, 1 team with a brand new stadium they got for practically nothing and another in QPR who have deep pockets.
If he wants to Roman it of course then none of that will matter; if he wants to spend less then QPR could be a cautionary tale that it's not all that easy ... even in London.
Fair points, but what drives London as a location is not domestic fans, but internationals. United, Chelsea, and Arsenal are not growing revenues within the borders of the UK as much as they are abroad. Adidas didn't sign a $300MM/10-year shirt deal with Chelsea based on UK sales.
I think people choose overseas teams based on success, not their location in the home league's country. If the most successful team of the past 10 years was Leeds they'd have a crap-load of overseas fans too.
I doubt the average casual fan who buys RS kits could pick out Liverpool on a map ... but they buy the shirts.
As far as buying an NFL team in Jacksonville is concerned, it's much cheaper than buying Dallas or New York. Since NFL teams share TV revenue evenly and have a salary cap in place for player wages, it's not difficult at all to build a winner with the right combination of players and staff in any US city.
Tell that to Cleveland.
I get your point but it's still a very unglamorous city with major attendance problems and zero brand (aside from the inherent brand of the NFL which is massive). I doubt the value of that franchise will grow any faster than just inflation on the value of any NFL franchise. If he moves to London and that doesn't work out it could even lose some value. It is a fairly safe bet in general though I would agree.
I don't think this guy could buy a London franchise, however (someone else mentioned this.) I'm pretty sure the NFL will not allow multiple franchises per owner.
Do you mean the NFL won't allow one of their owners to buy another team? I have heard people say that but the exact rule is "that they can own teams in other sports if those teams are in the same city as the NFL franchise they own or in a city where there is no NFL team." He could potentially pass that test on either condition.