Betting on appreciation is always a gamble.

Your friend the seller's gamble is that he'll be able to sell the place for his asking price in As-Is condition.

. $3000 to $10000 houses are probably in the part that never will, but maybe it will it's a gamble. 

Hi Everyone,I am considering to have my first real estate investment in the UK, specifically Manchester.I am very new to real estate and I am at my very first steps learning about it (BP, books, courses, etc.).

Otherwise it seems more like gambling than investing and I am not a gambler.

Try looking at: Why the BRRRR Method is a Risky Gamble for Out of State Investing

Like everyone mentioned, betting strictly on appreciation is a gamble. 

Where I live in the uk the whole duplex and triplex etc doesn't exist .There is a couple of duplex's dotted around but they are the same Price as 2 single family homes and get the same rent in terms of scaling I've seen bigger pockets podcasts explain you can't keep doing single family rentals , you need to move onto a quad plex etc. 

I thought it was an extreme gamble, and that he could lose everything.

Then they have to go back on the market and unless they do get a cash offer (which idk about your market but in mine it's a gamble) then they are still looking at 30+ days plus any days on market before receiving that.