Accumulating BTC gradually is not affordable for everyone, but it's quite affordable overall. Bitcoin transaction fee is normally very low, but again, even $0.3 is not nothing in some countries, for some people. Moreover, you do need to be able to save up and also afford to lose your savings when you're accumulating Bitcoin, so those who can barely make ends meet are also unable to go down that road. Finally, while I do agree that a bit of BTC is better than no BTC, it can be quite insignificant if you have a very small amount. For example, if over 1 year, you accumulate $200 of BTC, then even if BTC costs over $1 million, it's just $2k for you. And sure, it's not nothing, but there are very few cases in which this amount of money can be truly life-changing.
In fact, accumulating BTC gradually is quite easy, and Bitcoin transaction fees aren't even a barrier. However, it is important to realize that this requires strong determination and fundamental confidence. If someone gradually saves or installs Bitcoin at a rate of $1 per day, it could grow to around $365 in a year. Well, it doesn't have to be every day,it could be saving fiat for 10-30 days and then exchanging it for Bitcoin, so makes it easier. Furthermore, if Bitcoin experiences a decline in value, this will be a discount or additional support, and can be an opportunity to accumulate even more Bitcoin. Hopefully, during that period, we might have additional income, whether from additional work/overtime, getting a project to work on, etc., which can also be used to accumulate Bitcoin in installments.