imo, it's better not to think the old trader is an outstanding trader (I mean a oustanding investor.) until you actually find out his real return on investment... One of my ex-lecturers who claims to be a portfolio manager of some billion worth US mutual fund, has no proven record and no practical knowledge of financial investment. He only bluffs ...besides, his car is really old...
He used to sitting to the glass window (face to street), open to public in street, so that I can easily take a photo long distance outside silently. He was saying that he sleep in home, so that he pay bus and coffee in the specific place in the coffee shop, just to avoid sleeping. I felt he is worth to do that every day.
I know 95% of traders is a loser in the long run. However OP is not related to possible bluff and his record. And ".besides, his car is really old..." is not an issue for deciding a good trader. Lots of wealthy person drive old car and wear old cloths. Possibly it is reason why he became wealthy. I am saying he bring his MS surface laptop evey day and buy coffee every day to spend hours to program Excel Visual Basic which was his primary tool for his (recent 30 years) life, unlike the many 30's and 40's with primary tool in C++, C#, Python and R. Possibly that is a new culture and a new living style, not like a jerky in lotto shop and casino.
I had a favorite coffee shop in California. One old guy used to be there every day for an hour or two, he was bigtime trader, he made his living at it at least. Not daytrading exactly, seemingly more like swing trader. He wasn't exactly a mechanical trader, very superstitious actually. He wouldn't bathe sometimes, said it was bad luck! He'd smell bad leading up to FOMC meetings.. He never shared much with me, I was working on software and algo trading, he was interested but never intruded on me. I never intruded on him. He was interesting guy, drove a very nice car as I recall, dressed well too... Regarding the wifi security you can encrypt the last mile... I love coffee shops, I can't work at home sometimes, same boring shit all day, people asking me to do some stupid things for them, lots of useless noise from people that don't value quiet, goddam tv's going when nobody is watching them... these are all adults past middle aged too, stupider than little kids... usually people in coffee shops have triple digit iq's...
You may find when you reach his age the comfort of a coffee shop. And also that if he made good money in his younger days, it is now 'winning' that gives him pleasure. Getting old is the pits, and values change dramatically. So rather than wonder about his PnL, prepare yourself, because where he is now you will be!!
I go to Starbucks 2-3 hours most days, I use their Wifi for email but I use Verizon Hub for day trading. You use gift card so long, Starbucks sends you their gold gift card, so many visits you get free drink and free refills of regular coffee. Some Starbucks near colleges give you password on your receipt/2 hour limit and others don't care how long you there. You go long enough, employees now who you are, some old fart with a laptop that tips nicely, they just bring me coffee when cup runs out, they have oatmeal or bagels about only healthy thing you can buy. But there no way I would trade off their Wifi, way to many hackers these days. I know one guy who fixes computers, and does it only at Starbucks, he saving office rental space, saw another guy doing tax returns, financial planners, Insurance salespersons and even Amway selling.
I saw a coffee shop that has a fixed location of PC, for common use by coffee buyer, losing a space of two chair.
As an ET suggestion for the future, I hope ET owner/manager makes a column for coffee shop location (favorable to traders) by each city. It is like the gamblers forum, with casino lists nearby each city. Anyway tell me if there is one in Manhattan.
http://nycstarbucks.com/ 212 Starbucks in New York City and open for 365 days...that's even better than Forex market ... Good luck in finding big time traders at café