The most important thing is to start consistently, not the amount of Bitcoin. To start any investment, you should first have money, sufficient knowledge, or absolutely perfect market conditions.
Whether you are a pensioner, a student, a low-wage earner, or someone who has something in hand at the end of the month you can still be a successful investor in the world of Bitcoin—if you are consistent.
For those who have a long-term view of Bitcoin investments, the main objective should be to hold on to time. Whether big or small, this is your real capital. You need to see each day, each week, or each month as an opportunity—not in the light of market momentum or news. Small steps make a big difference in the long run.
Obviously there is nothing like absolute perfect market condition, if you want to invest in Bitcoin, every market condition in Bitcoin is perfect for investment as the market price is not on a fixed deposit, what investors do is to see through this conditions and go ahead with their investment plan. However I totally agree with you on the other points you made concerning the strata of persons that should get involved in Bitcoin investment as it's open for all determine persons and the idea of starting from the cradle consistently.