Without having patience to hodl for a long term you won't make it that big and sometimes you will end up losing money but if you are patient enough to hodl for long term then you will definitely reap big.
And without a Backup funds you will easily be tempted to dip hands into your Bitcoin investment when ever you have emergency or problem and you are not with cash but when you have a backup funds it will help you in times of emergency or problem.
So it is very important to protect your investment, especially investments as volatile as Bitcoin, to avoid unnecessary losses. So it will be a very good move to build your backup funds, while contemporaneously building your Bitcoin, although it may slow down your accumulation speed and may take a bit longer to reach your financial goals, however it's all good as long as your backup funds are being built gradually and strong, because the backup funds are just as important as the investment itself. However, it's more preferable engaging in a slow but steady accumulation with a strong financial backup, than being aggressive with one's accumulation with no strong financial backup which will later lead to one's down fall.
You have a good point if I must say and I believe those who did not have plans in investment are the ones who are not patient. Also, the backup plans of a thing in commensurate with the amount invested sounds like a good plan, but don't you think that if you want to HODL, it might take many years? Can the person guarantee such backup funds to take care of his finances for that long? I doubt that. Otherwise, there will not be time for an investment at all to have had such a big money you narrated secured before being able to invest.
This is why I think you exaggerate this backup plan of a thing, a viable source of income is enough here. With that, you can meet your needs financially and even save more or invest more. Above all, my advice is that if you are investing, the money you invested should be treated as if you don't have it again, then carry on with your life as usual. If you didn't have that invested money, wouldn't you survive? That's the spirit! Nevertheless, having a few excesses that will take care of the immediate needs is still very important to avoid being stranded, but certainly can't be the kind of backup plan you explained.