Heavy positions should always be placed on mainstream coins, and one should never bet heavily on altcoins.
The essence of altcoins is to exploit inexperienced investors; every bull market brings a surge of new altcoins, and the popular altcoins from the previous cycle are often replaced by new star projects in the next bull market, gradually being forgotten by the market.
For those without insider information or channels, it is nearly impossible to buy into altcoins before they explode. In most cases, people only learn about an altcoin after it has skyrocketed, but by then, chasing the price is often too late. Even if one is lucky enough to catch a wave of growth, more often than not, they face fluctuations and declines.
Altcoins are highly volatile, making it difficult for ordinary investors to hold them for the long term; both gains and losses can occur, often earning a small profit a few times but suffering a significant loss once, leading to an overall loss.