In other words you've identified Bitcoins as a high risk, high reward investment and have brought a small amount to balance risk and reward.
Exactly. In ten years time, my "retirement bitcoins" will either be worth nothing, or will be worth enough for a comfortable retirement.
There's no need to hold a lot of coins, because no-one needs "twice a comfortable requirement", if you know what I mean.
I'm not saying how many I have, but elsewhere on this forum Vladimir suggested 2100 bitcoins (one ten-thousandth of the total amount) for a long-term investment fund, and I think that's a wise suggestion. It's still possible for a determined user to buy mining equipment to gain that many, or to buy that many on the open market with some investment funds. But of course you need to accept the possibility of losing your investment if Bitcoin somehow fails.