It's not enough having an investment plan, knowing the right choice to make for every investment defines the investor better. Take for example jumping on every new coin we find on reputable exchange might not be enough guarantee that coin will do well in the future.
Why do people believe in bitcoin more than other coins, the answer is because bitcoin has the power to defend itself in the market. Meanwhile, other coins have no potential and usually people only use them in the short term to gain profits because there is a risk that sometimes makes someone lose their money.
Some coin might have good Supply but low liquidity, some might have high market capitalisation but very poor volatility. Although it's hard to predict the accuracy of a coin performance in the near future this why it is always advised to stick to the known which is BTC.
Another option is to spread ones portfolio amongst different coins but ensuring the have a greater percentage in projects with a visible future. It is better to win small and lose less than lose more and win less
Not all coins have the ability to be good under certain conditions and even when we start searching in the top 10 coinmarketcap maybe only some have the ability to generate profits and the rest are much more speculative and there is a much greater risk when involved in them Moreover if the concept is maintained for the long term then such coins will have far less potential to generate maximum profits.
If you intend to spread your portfolio then you should look for coins that have potential and you have to see to what extent these coins can generate profits. Otherwise people will put themselves in a much more risky situation and therefore it is important to know the journey of coins first before investing them.