So it is better to save at initial stage and once you hold a good capital invest it.
You are totally wrong on this . Big capital isnt the sole things that you need for investment because the interest rate mostly stay the same or differ a bit but the fact is that you can still invest with a fraction of your money but this will only gets you a smaller interest gain.
What matters most will be your capital control ( financial management ) because without it you can lose it all to a bogus investment with a blink of an eye. Also it is kinda funny to see this, saving to put it into investment later on because investment is kinda like speculation which is unpredictable( things might get south to your savings )
But with big capital the payout from each interest will be bigger too although the interest is low, for example like you put $100 interest 5%= $2, then you put $1000 with 3% of your interest the result is bigger than small capital. Although investment still have a high risk too but there are still a solid investment out there. Except gambling I dont think you will lose your capital just with a blink if an eye, because others investment sure give you some payment too so at least you wont lose all of your money there