How to solve the problem of rafters with a wide pitch?

I am considering buying an unfinished house, where the attic floor is apparently saved.

The size of the house on the outer walls is somewhere 9 * 12 meters. For some reason the pitch of the rafters is about 110-120 cm. The roof is not insulated, with a membrane, counter battens seem to be there. The roof stands for about 4-5 years, ie snow, wind withstood.

The expert after examination said – to disassemble the roof, add rafters, and do insulation from the outside, then again to assemble.

I do not want to do this for the reasons: 1) expensive; 2) no assurance that spending money will come back without flaws. No reliable, trusted builders in sight.

I would like to listen to the decision to buy, advice from experienced people, whether there is a way to strengthen the existing rafters without disassembling the roof. Since the main fear of such an assembly – that the roof will fly off.

For example, propping the rafters with rafters along the low wall, or propping them in several places with posts, which will become the frame of the interior walls, etc. Don't want to give up this option, please help!

Or maybe there is nothing wrong with such a roof?

And insulate the bottom somehow, and myself can, though it will be worse than the disassembly of the roof, but this can probably be compensated by the thickness of the 2 layers of insulation.