I collect simply for the joy and beauty of Indian coins which I can afford within my budget. I don't think about RRRRs - risk, reward, return, rarity. A battered ancient copper gives me same joy as a UNC Mohur. I do have my own personal favorites but overall I don't differentiate between any coin based on its metal, age, condition etc. Each and every individual coin gives me equal pleasure. The fun is studying and researching them, analysis and interpreting them, simply gazing and marveling at them, and gaining nirvana in the process.
Buying for investment, and many indeed do, is not a good idea as all asset classes, across markets, go up and down based on many factors viz popularity, new finds, changing tastes and preferences, market rigging etc. An investor may lose interest if the value of his holding declines but a collector is indifferent because price benchmark at any given point of time that doesn't bother him in both relative or absolute terms.
For me personally, the joy of collecting is based on the inherent and underlying knowledge you gain that far outweighs monetary consideration. If I get the coin I want, I feel blessed but don't fret over it if I lose as the quest continues. Que sara sara.......to each his own I guess.
Happy collecting.