Yes, agreed. There are no prior or current instruments that parallel BTC in which to base long-term performance expectations. That was part of my point.
People wish to attribute BTC with expectations of long-term appreciation and price stability, but I've yet to learn where these very desirable properties will actually come from. Unlike other properties of bitcoin, neither of these are encoded or enforced. So what gives the claim of future price stability credence?
Until someone comes up with some plausible mechanism, I think this goes in the category of unicorns and free energy. Buy-and-hold strategies may be great advice for a basket of stocks, but this is hardly sound advice for BTC. Even if someone gifted you a large stash of BTC, holding that position in BTC long-term isn't rooted in any sound logic or real comparison.
Just because BTC is attractive for global low-cost transactions doesn't in and of itself give bitcoin any inherent minimum value per coin, or curb the price volatility of those that need to transact instead of hoard.