So you think that corporations, one of the foundations of capitalism, cheat all their workers.
No. How did you reach that conclusion?
The economy isn't full of people who are being cheated, it's largely full of people who have no idea how to utilise the money they have. That someone is writing a letter asking whether to spend it shows that. The less they have, the better and their role is to get rid of what they have. If they find beggars to help them do that, why not?
Indeed, the chances are high she is in debt, fulfilling her role of having as little as possible for years into the future - thus making her less rich than the beggar who only has nothing, or maybe even a fiver. Perhaps the stigma he talks about by being a beggar is the same as that in being rich, you've got more than everyone else?

I think my point was more that how an individual gets the resources / money he/she gets and how an individual utilises them and adapts to whatever changes occur, is more key to the success and future of that individual than some economist's statistical / high level overview about how an economy will work and what good / bad things would happen if you give a beggar money or not. [or do anything with your money or life based upon his hand-waving overview] It's like the "can I make money playing the piano?" questions in the forum. Of course you can't, unless you're one of the people that do.
Or, in other words, just because everyone can't make money begging [or doing anything else] doesn't mean someone can't and just because a lot of people will get a £1 from farming or £1+ from begging, but not both and would stop at that stage forever. There are a few who will do both jobs with an eye on using the extra money to let them do something else, rather than buy a bigger TV or feed another 5 beggars on their next holiday.
In most cases for the role of beggar, we aren't going to worry too much about the fact Tim tells us we can't be one. However, he'll tell you the same thing about running Tescos if you ask him whether you should do that. "If everyone ran Tescos, who would farm?"
Clearly people giving money away are unlikely to do anything of value with it. The fact someone who begs might do was the point of my story. The anti-thesis to his point which is that they might not - albeit he couched it in terms that they would not, and claimed not only that, but they should be doing something else. No one can predict the future, but we've got to get the money from her to someone else somehow.
Albeit, the corporations, with a proven track record, might be a better bet, so if you're unsure about your beggar's future with your money, tell her to buy some shiny things from some other guy that isn't farming either.
Whether I give my money away to beggars, buy a lottery ticket or a buy a piano the money will have gone from me and for those particular cases, although there are small possibilities that I might make more money from them, chances are I won't. It's called disposable income for a reason.
At some point in the future, there may not be an industry in piano building, begging from richer tourists, selling lottery tickets or anything else. Perhaps I shouldn't buy a piano or a lottery ticket, or anything else, in order to avert the situation where piano builders et al get fooled into thinking they can make more money at it with less effort than farming for £1 a week.
Worse, if farmers were to leave the fields and make pianos or sell lottery tickets, we can all see the harm. There'd be more pianos and lottery tickets and no cabbage. Tim is effectively telling her to stop spending money on anything unless it involves farming or unless everyone can do it.
Clearly the future changes and those changes might influence whether what we do works and gets us the money we want in the short, medium or long term. Begging might not be a long term strategy, but neither was working in British industry for a lot of people.