These bikes love to be ridden. Regularly. Bike kept in good condition in original condition hold their value better than a restored bike.
Value for money is what you have now with low mileage bike. If the maintenance is kept up, oil changes, servicing with regular detailing there is no reason the engine can't do 50,000 miles. some have done more than this with good care an a lot have done less with not so good care.
The only thing that may catch you is the front cam-chain guide. These do de laminate and the engine ha to be removed to take the head off to get at the guide. My thinking is, that it is because the engine hasn't been used regularly in turn the guide rubber dries out and gets brittle. With regular use they seem to last a lot longer.
The bottom oil strainer. has a tendency to blow a hole in it. Letting the engine warm up and riding sedately for the first couple of miles till the oil thins help to save the strainer. Do check the bottom strainer as a preventative and maintenance issue. Lot of info on repairing the exiting strainer rather than buying a new one as the problem will happen to these as well. There are some aftermarket ones, (mainly Heiden Tuning), that offer a different tyled one that don't seem to have any issues.
If you done 4-5000 miles per year an kept the bike for 5 years with regular maintenance and no engine dramas and kept in good condition, you could expect to get more money than you have invested in it. May even come out even after spending on, tyres, brake pads and chain and sprocket.
Get a volt meter to keep an eye on your charging system. The rotor is 40 years old and the rein could be breaking down with age. Then again it may lat 20-30,000 mile but it would pay to keep an eye on it. If the rotor does go bad a member here does excellent rewinds for a good price and that is all that will usually go wrong with these bikes. Brushes are a wear item but with ssuch low miles you wouldn't/shouldn't have a problem for years. Keep the battery in good condition, a bad battery is one of the main culprits to causing the rotor to be overworked leading to overheating.
Ride the bike and enjoy it.