PayPal's shares were one of the best market performers Tuesday despite the tie-up between Global Payments and Total System Services that's worth $21.5 billion of stock, CNBC's Jim Cramer said.

The stock climbed 1.72% during the same session, while two major indexes declined nearly 1%.

"Every time you see competitors teaming up to try to take share from PayPal, it just reminds people how these guys are already the undisputed worldwide leader in payments, which is what makes this such a fabulous fintech stock," the "Mad Money" host said.

After the Global Payments and Total System Services merger was announced, investors began speculating that it could dent the market share that both PayPal and Cash App-parent Square Inc. have accumulated, Cramer said.

With Braintree and Venmo under its umbrella, PayPal is "the real juggernaut" of the financial technology sector under CEO Dan Schulman's leadership, he said. Furthermore, Square has done a lot to simplify the cash register and electronic payments with its card reader, not to mention its lending services to small businesses, he added.

Square has a market cap of about $28 billion, which pales in comparison to PayPal's more than $131 billion stronghold.

"The merger makes a ton of sense," Cramer said. "Sometimes, though, the fight isn't worth winning."

Get Cramer's full insight here