No, Stellar is not a PoW coin. Can stellar lumens reach $100? That is highly unlikely as it would mean a price increase of 1500x over the current levels. Assuming the BTC/XLM ratio stays the same, it would mean bitcoin is at $12.5 million per coin. 
Not quite a correct calculation, exactly behind the bitcoin rate is almost no coin, the price of coins depends on the popularity and use, and popularity today plays a major role, if the team from stellar will invest in the right PR, the price can easily reach even your 100 dollars).
You're correct that the price of a cryptocurrency is influenced by various factors, and popularity is indeed a significant one. Projects with strong community support, effective marketing, and real-world use cases often attract more attention and demand.
Public relations (PR) efforts, marketing strategies, partnerships, and overall project visibility can play a crucial role in shaping the perception and popularity of a cryptocurrency. Stellar (XLM) or any other coin has the potential for price appreciation if the project team effectively communicates its value proposition and expands its user base.
However, it's important to note that predicting specific price levels for cryptocurrencies is highly speculative. The market is influenced by numerous dynamic factors, and prices can be volatile. Investors should conduct thorough research, stay informed about project developments, and consider their risk tolerance when making investment decisions.