Currently Bitcoin is expected to have a bull run and halving in coming time as we all know it.

Now if you were to make an investment of $100 as a beginner regardless of your country and as it stands Bitcoin is experiencing a bear market (an example) after you made 5% capital.

Initially you want to hold for a very long time but as a result of the bear market you loose your capital and half your investment yet the market is showing no sign for you to recover.
What's your next step as a first timer in Bitcoin /Altcoin trading?

There are two questions, one for Bitcoin and another one for Altcoin.

Your question is confusing too, trading and investing (holding) are different. If you are a trader, you must know you are not planning to hold and you must be disciplined to exit the market.

Holding is for investing, not for trading.

Bitcoin is a strongest cryptocurrency so after a bear market, it won't die and it will be a first cryptocurrency to recover from a market bottom.

Altcoins are not as strong as Bitcoin and they can die in a bear market. Even Bitcoin triggers a bull market, many altcoins can not recover to their past all time highs.

Risk with trading and investing in altcoins are bigger with trading and investing in Bitcoin.