Combination of RU and Fin/Dut

[LongWayHome]

Hello everyone, as a person who's going to buy 10g of RU next month,
I have an important question that I bet many people ask themselves too:

When I travel on forums, in my walkabouts, I see a lot of people if it's here,
*** or HLH, that use RU along with Fin OR Dut, and I seem to wonder...why?
I'd like to think that RU might be enough for halting hair loss, or slow it down, and even regrow, but the main thing is maintaining, and when I see those people I ask myself is it because RU's just not doing it's job? then why use it? or they maybe just want to get the strongest reaction? If RU's price was like fina's/duta's, I wouldn't even bother to start thinkin about it, but it's not like that at all.
RU is too expensive, and when I hear about so many people that use it, as I said I'd like to think this is because it's doing it's job properly.
But when you use fin along with it, it means you don't have sides/don't care about them, so why the hell to use RU in the first place when it's so expensive?

Please don't be a douche, answer this seriously. I'm about to spend half of my salary on RU and this is without KB and the miligram measure thing.

Thank you.